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root/crypto/pcbc.c

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DEFINITIONS

This source file includes following definitions.
  1. crypto_pcbc_setkey
  2. crypto_pcbc_encrypt_segment
  3. crypto_pcbc_encrypt_inplace
  4. crypto_pcbc_encrypt
  5. crypto_pcbc_decrypt_segment
  6. crypto_pcbc_decrypt_inplace
  7. crypto_pcbc_decrypt
  8. crypto_pcbc_init_tfm
  9. crypto_pcbc_exit_tfm
  10. crypto_pcbc_alloc
  11. crypto_pcbc_free
  12. crypto_pcbc_module_init
  13. crypto_pcbc_module_exit

/*
 * PCBC: Propagating Cipher Block Chaining mode
 *
 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * Derived from cbc.c
 * - 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/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>

struct crypto_pcbc_ctx {
        struct crypto_cipher *child;
};

static int crypto_pcbc_setkey(struct crypto_tfm *parent, const u8 *key,
                              unsigned int keylen)
{
        struct crypto_pcbc_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_pcbc_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);
                crypto_xor(iv, src, bsize);

                src += bsize;
                dst += bsize;
        } while ((nbytes -= bsize) >= bsize);

        return nbytes;
}

static int crypto_pcbc_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;
        u8 tmpbuf[bsize];

        do {
                memcpy(tmpbuf, src, bsize);
                crypto_xor(iv, src, bsize);
                fn(crypto_cipher_tfm(tfm), src, iv);
                memcpy(iv, tmpbuf, bsize);
                crypto_xor(iv, src, bsize);

                src += bsize;
        } while ((nbytes -= bsize) >= bsize);

        memcpy(walk->iv, iv, bsize);

        return nbytes;
}

static int crypto_pcbc_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_pcbc_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_pcbc_encrypt_inplace(desc, &walk,
                                                             child);
                else
                        nbytes = crypto_pcbc_encrypt_segment(desc, &walk,
                                                             child);
                err = blkcipher_walk_done(desc, &walk, nbytes);
        }

        return err;
}

static int crypto_pcbc_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);
                memcpy(iv, src, bsize);
                crypto_xor(iv, dst, bsize);

                src += bsize;
                dst += bsize;
        } while ((nbytes -= bsize) >= bsize);

        memcpy(walk->iv, iv, bsize);

        return nbytes;
}

static int crypto_pcbc_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 *iv = walk->iv;
        u8 tmpbuf[bsize];

        do {
                memcpy(tmpbuf, src, bsize);
                fn(crypto_cipher_tfm(tfm), src, src);
                crypto_xor(src, iv, bsize);
                memcpy(iv, tmpbuf, bsize);
                crypto_xor(iv, src, bsize);

                src += bsize;
        } while ((nbytes -= bsize) >= bsize);

        memcpy(walk->iv, iv, bsize);

        return nbytes;
}

static int crypto_pcbc_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_pcbc_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_pcbc_decrypt_inplace(desc, &walk,
                                                             child);
                else
                        nbytes = crypto_pcbc_decrypt_segment(desc, &walk,
                                                             child);
                err = blkcipher_walk_done(desc, &walk, nbytes);
        }

        return err;
}

static int crypto_pcbc_init_tfm(struct crypto_tfm *tfm)
{
        struct crypto_instance *inst = (void *)tfm->__crt_alg;
        struct crypto_spawn *spawn = crypto_instance_ctx(inst);
        struct crypto_pcbc_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_pcbc_exit_tfm(struct crypto_tfm *tfm)
{
        struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(tfm);
        crypto_free_cipher(ctx->child);
}

static struct crypto_instance *crypto_pcbc_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 = crypto_alloc_instance("pcbc", 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_pcbc_ctx);

        inst->alg.cra_init = crypto_pcbc_init_tfm;
        inst->alg.cra_exit = crypto_pcbc_exit_tfm;

        inst->alg.cra_blkcipher.setkey = crypto_pcbc_setkey;
        inst->alg.cra_blkcipher.encrypt = crypto_pcbc_encrypt;
        inst->alg.cra_blkcipher.decrypt = crypto_pcbc_decrypt;

out_put_alg:
        crypto_mod_put(alg);
        return inst;
}

static void crypto_pcbc_free(struct crypto_instance *inst)
{
        crypto_drop_spawn(crypto_instance_ctx(inst));
        kfree(inst);
}

static struct crypto_template crypto_pcbc_tmpl = {
        .name = "pcbc",
        .alloc = crypto_pcbc_alloc,
        .free = crypto_pcbc_free,
        .module = THIS_MODULE,
};

static int __init crypto_pcbc_module_init(void)
{
        return crypto_register_template(&crypto_pcbc_tmpl);
}

static void __exit crypto_pcbc_module_exit(void)
{
        crypto_unregister_template(&crypto_pcbc_tmpl);
}

module_init(crypto_pcbc_module_init);
module_exit(crypto_pcbc_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("PCBC block cipher algorithm");

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