diff options
Diffstat (limited to 'crypto/cbc.c')
-rw-r--r-- | crypto/cbc.c | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/crypto/cbc.c b/crypto/cbc.c new file mode 100644 index 00000000..61ac42e1 --- /dev/null +++ b/crypto/cbc.c @@ -0,0 +1,291 @@ +/* + * CBC: Cipher Block Chaining mode + * + * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> + * + * 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 <crypto/algapi.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/log2.h> +#include <linux/module.h> +#include <linux/scatterlist.h> +#include <linux/slab.h> + +struct crypto_cbc_ctx { + struct crypto_cipher *child; +}; + +static int crypto_cbc_setkey(struct crypto_tfm *parent, const u8 *key, + unsigned int keylen) +{ + struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(parent); + struct crypto_cipher *child = ctx->child; + int err; + + crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); + crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) & + CRYPTO_TFM_REQ_MASK); + err = crypto_cipher_setkey(child, key, keylen); + crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) & + CRYPTO_TFM_RES_MASK); + return err; +} + +static int crypto_cbc_encrypt_segment(struct blkcipher_desc *desc, + struct blkcipher_walk *walk, + struct crypto_cipher *tfm) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_encrypt; + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + u8 *iv = walk->iv; + + do { + crypto_xor(iv, src, bsize); + fn(crypto_cipher_tfm(tfm), dst, iv); + memcpy(iv, dst, bsize); + + src += bsize; + dst += bsize; + } while ((nbytes -= bsize) >= bsize); + + return nbytes; +} + +static int crypto_cbc_encrypt_inplace(struct blkcipher_desc *desc, + struct blkcipher_walk *walk, + struct crypto_cipher *tfm) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_encrypt; + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 *iv = walk->iv; + + do { + crypto_xor(src, iv, bsize); + fn(crypto_cipher_tfm(tfm), src, src); + iv = src; + + src += bsize; + } while ((nbytes -= bsize) >= bsize); + + memcpy(walk->iv, iv, bsize); + + return nbytes; +} + +static int crypto_cbc_encrypt(struct blkcipher_desc *desc, + struct scatterlist *dst, struct scatterlist *src, + unsigned int nbytes) +{ + struct blkcipher_walk walk; + struct crypto_blkcipher *tfm = desc->tfm; + struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm); + struct crypto_cipher *child = ctx->child; + int err; + + blkcipher_walk_init(&walk, dst, src, nbytes); + err = blkcipher_walk_virt(desc, &walk); + + while ((nbytes = walk.nbytes)) { + if (walk.src.virt.addr == walk.dst.virt.addr) + nbytes = crypto_cbc_encrypt_inplace(desc, &walk, child); + else + nbytes = crypto_cbc_encrypt_segment(desc, &walk, child); + err = blkcipher_walk_done(desc, &walk, nbytes); + } + + return err; +} + +static int crypto_cbc_decrypt_segment(struct blkcipher_desc *desc, + struct blkcipher_walk *walk, + struct crypto_cipher *tfm) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_decrypt; + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + u8 *iv = walk->iv; + + do { + fn(crypto_cipher_tfm(tfm), dst, src); + crypto_xor(dst, iv, bsize); + iv = src; + + src += bsize; + dst += bsize; + } while ((nbytes -= bsize) >= bsize); + + memcpy(walk->iv, iv, bsize); + + return nbytes; +} + +static int crypto_cbc_decrypt_inplace(struct blkcipher_desc *desc, + struct blkcipher_walk *walk, + struct crypto_cipher *tfm) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_decrypt; + int bsize = crypto_cipher_blocksize(tfm); + unsigned int nbytes = walk->nbytes; + u8 *src = walk->src.virt.addr; + u8 last_iv[bsize]; + + /* Start of the last block. */ + src += nbytes - (nbytes & (bsize - 1)) - bsize; + memcpy(last_iv, src, bsize); + + for (;;) { + fn(crypto_cipher_tfm(tfm), src, src); + if ((nbytes -= bsize) < bsize) + break; + crypto_xor(src, src - bsize, bsize); + src -= bsize; + } + + crypto_xor(src, walk->iv, bsize); + memcpy(walk->iv, last_iv, bsize); + + return nbytes; +} + +static int crypto_cbc_decrypt(struct blkcipher_desc *desc, + struct scatterlist *dst, struct scatterlist *src, + unsigned int nbytes) +{ + struct blkcipher_walk walk; + struct crypto_blkcipher *tfm = desc->tfm; + struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm); + struct crypto_cipher *child = ctx->child; + int err; + + blkcipher_walk_init(&walk, dst, src, nbytes); + err = blkcipher_walk_virt(desc, &walk); + + while ((nbytes = walk.nbytes)) { + if (walk.src.virt.addr == walk.dst.virt.addr) + nbytes = crypto_cbc_decrypt_inplace(desc, &walk, child); + else + nbytes = crypto_cbc_decrypt_segment(desc, &walk, child); + err = blkcipher_walk_done(desc, &walk, nbytes); + } + + return err; +} + +static int crypto_cbc_init_tfm(struct crypto_tfm *tfm) +{ + struct crypto_instance *inst = (void *)tfm->__crt_alg; + struct crypto_spawn *spawn = crypto_instance_ctx(inst); + struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm); + struct crypto_cipher *cipher; + + cipher = crypto_spawn_cipher(spawn); + if (IS_ERR(cipher)) + return PTR_ERR(cipher); + + ctx->child = cipher; + return 0; +} + +static void crypto_cbc_exit_tfm(struct crypto_tfm *tfm) +{ + struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm); + crypto_free_cipher(ctx->child); +} + +static struct crypto_instance *crypto_cbc_alloc(struct rtattr **tb) +{ + struct crypto_instance *inst; + struct crypto_alg *alg; + int err; + + err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); + if (err) + return ERR_PTR(err); + + alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER, + CRYPTO_ALG_TYPE_MASK); + if (IS_ERR(alg)) + return ERR_CAST(alg); + + inst = ERR_PTR(-EINVAL); + if (!is_power_of_2(alg->cra_blocksize)) + goto out_put_alg; + + inst = crypto_alloc_instance("cbc", alg); + if (IS_ERR(inst)) + goto out_put_alg; + + inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; + inst->alg.cra_priority = alg->cra_priority; + inst->alg.cra_blocksize = alg->cra_blocksize; + inst->alg.cra_alignmask = alg->cra_alignmask; + inst->alg.cra_type = &crypto_blkcipher_type; + + /* We access the data as u32s when xoring. */ + inst->alg.cra_alignmask |= __alignof__(u32) - 1; + + inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize; + inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize; + inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize; + + inst->alg.cra_ctxsize = sizeof(struct crypto_cbc_ctx); + + inst->alg.cra_init = crypto_cbc_init_tfm; + inst->alg.cra_exit = crypto_cbc_exit_tfm; + + inst->alg.cra_blkcipher.setkey = crypto_cbc_setkey; + inst->alg.cra_blkcipher.encrypt = crypto_cbc_encrypt; + inst->alg.cra_blkcipher.decrypt = crypto_cbc_decrypt; + +out_put_alg: + crypto_mod_put(alg); + return inst; +} + +static void crypto_cbc_free(struct crypto_instance *inst) +{ + crypto_drop_spawn(crypto_instance_ctx(inst)); + kfree(inst); +} + +static struct crypto_template crypto_cbc_tmpl = { + .name = "cbc", + .alloc = crypto_cbc_alloc, + .free = crypto_cbc_free, + .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 algorithm"); |