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4de437265e
Commit9ae433bc79
("crypto: chacha20 - convert generic and x86 versions to skcipher") ported the existing chacha20 code to use the new skcipher API, and introduced a bug along the way. Unfortunately, the tcrypt tests did not catch the error, and it was only found recently by Tobias. Stefan kindly diagnosed the error, and proposed a fix which is similar to the one below, with the exception that 'walk.stride' is used rather than the hardcoded block size. This does not actually matter in this case, but it's a better example of how to use the skcipher walk API. Fixes:9ae433bc79
("crypto: chacha20 - convert generic and x86 ...") Cc: <stable@vger.kernel.org> # v4.11+ Cc: Steffen Klassert <steffen.klassert@secunet.com> Reported-by: Tobias Brunner <tobias@strongswan.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
144 lines
3.6 KiB
C
144 lines
3.6 KiB
C
/*
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* ChaCha20 256-bit cipher algorithm, RFC7539
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*
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* Copyright (C) 2015 Martin Willi
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <crypto/algapi.h>
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#include <crypto/chacha20.h>
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#include <crypto/internal/skcipher.h>
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#include <linux/module.h>
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static inline u32 le32_to_cpuvp(const void *p)
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{
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return le32_to_cpup(p);
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}
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static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes)
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{
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u8 stream[CHACHA20_BLOCK_SIZE];
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if (dst != src)
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memcpy(dst, src, bytes);
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while (bytes >= CHACHA20_BLOCK_SIZE) {
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chacha20_block(state, stream);
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crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);
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bytes -= CHACHA20_BLOCK_SIZE;
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dst += CHACHA20_BLOCK_SIZE;
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}
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if (bytes) {
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chacha20_block(state, stream);
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crypto_xor(dst, stream, bytes);
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}
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}
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void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv)
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{
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static const char constant[16] = "expand 32-byte k";
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state[0] = le32_to_cpuvp(constant + 0);
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state[1] = le32_to_cpuvp(constant + 4);
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state[2] = le32_to_cpuvp(constant + 8);
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state[3] = le32_to_cpuvp(constant + 12);
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state[4] = ctx->key[0];
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state[5] = ctx->key[1];
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state[6] = ctx->key[2];
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state[7] = ctx->key[3];
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state[8] = ctx->key[4];
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state[9] = ctx->key[5];
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state[10] = ctx->key[6];
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state[11] = ctx->key[7];
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state[12] = le32_to_cpuvp(iv + 0);
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state[13] = le32_to_cpuvp(iv + 4);
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state[14] = le32_to_cpuvp(iv + 8);
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state[15] = le32_to_cpuvp(iv + 12);
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}
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EXPORT_SYMBOL_GPL(crypto_chacha20_init);
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int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
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unsigned int keysize)
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{
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struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
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int i;
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if (keysize != CHACHA20_KEY_SIZE)
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return -EINVAL;
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for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
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ctx->key[i] = le32_to_cpuvp(key + i * sizeof(u32));
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return 0;
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}
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EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);
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int crypto_chacha20_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 chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
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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, true);
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crypto_chacha20_init(state, ctx, walk.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, walk.stride);
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chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
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nbytes);
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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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EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);
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static struct skcipher_alg alg = {
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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 chacha20_ctx),
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.base.cra_alignmask = sizeof(u32) - 1,
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.base.cra_module = THIS_MODULE,
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.min_keysize = CHACHA20_KEY_SIZE,
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.max_keysize = CHACHA20_KEY_SIZE,
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.ivsize = CHACHA20_IV_SIZE,
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.chunksize = CHACHA20_BLOCK_SIZE,
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.setkey = crypto_chacha20_setkey,
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.encrypt = crypto_chacha20_crypt,
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.decrypt = crypto_chacha20_crypt,
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};
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static int __init chacha20_generic_mod_init(void)
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{
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return crypto_register_skcipher(&alg);
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}
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static void __exit chacha20_generic_mod_fini(void)
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{
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crypto_unregister_skcipher(&alg);
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}
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module_init(chacha20_generic_mod_init);
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module_exit(chacha20_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("chacha20 cipher algorithm");
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MODULE_ALIAS_CRYPTO("chacha20");
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MODULE_ALIAS_CRYPTO("chacha20-generic");
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