diff options
Diffstat (limited to 'crypto/cbc.c')
| -rw-r--r-- | crypto/cbc.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/crypto/cbc.c b/crypto/cbc.c new file mode 100644 index 000000000..ed3df6246 --- /dev/null +++ b/crypto/cbc.c @@ -0,0 +1,187 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * CBC: Cipher Block Chaining mode + * + * Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au> + */ + +#include <crypto/internal/skcipher.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/log2.h> +#include <linux/module.h> + +static int crypto_cbc_encrypt_segment(struct crypto_lskcipher *tfm, + const u8 *src, u8 *dst, unsigned nbytes, + u8 *iv) +{ + unsigned int bsize = crypto_lskcipher_blocksize(tfm); + + for (; nbytes >= bsize; src += bsize, dst += bsize, nbytes -= bsize) { + crypto_xor(iv, src, bsize); + crypto_lskcipher_encrypt(tfm, iv, dst, bsize, NULL); + memcpy(iv, dst, bsize); + } + + return nbytes; +} + +static int crypto_cbc_encrypt_inplace(struct crypto_lskcipher *tfm, + u8 *src, unsigned nbytes, u8 *oiv) +{ + unsigned int bsize = crypto_lskcipher_blocksize(tfm); + u8 *iv = oiv; + + if (nbytes < bsize) + goto out; + + do { + crypto_xor(src, iv, bsize); + crypto_lskcipher_encrypt(tfm, src, src, bsize, NULL); + iv = src; + + src += bsize; + } while ((nbytes -= bsize) >= bsize); + + memcpy(oiv, iv, bsize); + +out: + return nbytes; +} + +static int crypto_cbc_encrypt(struct crypto_lskcipher *tfm, const u8 *src, + u8 *dst, unsigned len, u8 *iv, u32 flags) +{ + struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm); + bool final = flags & CRYPTO_LSKCIPHER_FLAG_FINAL; + struct crypto_lskcipher *cipher = *ctx; + int rem; + + if (src == dst) + rem = crypto_cbc_encrypt_inplace(cipher, dst, len, iv); + else + rem = crypto_cbc_encrypt_segment(cipher, src, dst, len, iv); + + return rem && final ? -EINVAL : rem; +} + +static int crypto_cbc_decrypt_segment(struct crypto_lskcipher *tfm, + const u8 *src, u8 *dst, unsigned nbytes, + u8 *oiv) +{ + unsigned int bsize = crypto_lskcipher_blocksize(tfm); + const u8 *iv = oiv; + + if (nbytes < bsize) + goto out; + + do { + crypto_lskcipher_decrypt(tfm, src, dst, bsize, NULL); + crypto_xor(dst, iv, bsize); + iv = src; + + src += bsize; + dst += bsize; + } while ((nbytes -= bsize) >= bsize); + + memcpy(oiv, iv, bsize); + +out: + return nbytes; +} + +static int crypto_cbc_decrypt_inplace(struct crypto_lskcipher *tfm, + u8 *src, unsigned nbytes, u8 *iv) +{ + unsigned int bsize = crypto_lskcipher_blocksize(tfm); + u8 last_iv[MAX_CIPHER_BLOCKSIZE]; + + if (nbytes < bsize) + goto out; + + /* Start of the last block. */ + src += nbytes - (nbytes & (bsize - 1)) - bsize; + memcpy(last_iv, src, bsize); + + for (;;) { + crypto_lskcipher_decrypt(tfm, src, src, bsize, NULL); + if ((nbytes -= bsize) < bsize) + break; + crypto_xor(src, src - bsize, bsize); + src -= bsize; + } + + crypto_xor(src, iv, bsize); + memcpy(iv, last_iv, bsize); + +out: + return nbytes; +} + +static int crypto_cbc_decrypt(struct crypto_lskcipher *tfm, const u8 *src, + u8 *dst, unsigned len, u8 *iv, u32 flags) +{ + struct crypto_lskcipher **ctx = crypto_lskcipher_ctx(tfm); + bool final = flags & CRYPTO_LSKCIPHER_FLAG_FINAL; + struct crypto_lskcipher *cipher = *ctx; + int rem; + + if (src == dst) + rem = crypto_cbc_decrypt_inplace(cipher, dst, len, iv); + else + rem = crypto_cbc_decrypt_segment(cipher, src, dst, len, iv); + + return rem && final ? -EINVAL : rem; +} + +static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb) +{ + struct lskcipher_instance *inst; + int err; + + inst = lskcipher_alloc_instance_simple(tmpl, tb); + if (IS_ERR(inst)) + return PTR_ERR(inst); + + err = -EINVAL; + if (!is_power_of_2(inst->alg.co.base.cra_blocksize)) + goto out_free_inst; + + if (inst->alg.co.statesize) + goto out_free_inst; + + inst->alg.encrypt = crypto_cbc_encrypt; + inst->alg.decrypt = crypto_cbc_decrypt; + + err = lskcipher_register_instance(tmpl, inst); + if (err) { +out_free_inst: + inst->free(inst); + } + + return err; +} + +static struct crypto_template crypto_cbc_tmpl = { + .name = "cbc", + .create = crypto_cbc_create, + .module = THIS_MODULE, +}; + +static int __init crypto_cbc_module_init(void) +{ + return crypto_register_template(&crypto_cbc_tmpl); +} + +static void __exit crypto_cbc_module_exit(void) +{ + crypto_unregister_template(&crypto_cbc_tmpl); +} + +module_init(crypto_cbc_module_init); +module_exit(crypto_cbc_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("CBC block cipher mode of operation"); +MODULE_ALIAS_CRYPTO("cbc"); |