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root/crypto/ctr.c

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DEFINITIONS

This source file includes following definitions.
  1. crypto_ctr_setkey
  2. crypto_ctr_crypt_final
  3. crypto_ctr_crypt_segment
  4. crypto_ctr_crypt_inplace
  5. crypto_ctr_crypt
  6. crypto_ctr_init_tfm
  7. crypto_ctr_exit_tfm
  8. crypto_ctr_alloc
  9. crypto_ctr_free
  10. crypto_rfc3686_setkey
  11. crypto_rfc3686_crypt
  12. crypto_rfc3686_init_tfm
  13. crypto_rfc3686_exit_tfm
  14. crypto_rfc3686_alloc
  15. crypto_ctr_module_init
  16. crypto_ctr_module_exit

/*
 * CTR: Counter mode
 *
 * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
 *
 * 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 <crypto/ctr.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>

struct crypto_ctr_ctx {
        struct crypto_cipher *child;
};

struct crypto_rfc3686_ctx {
        struct crypto_blkcipher *child;
        u8 nonce[CTR_RFC3686_NONCE_SIZE];
};

static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
                             unsigned int keylen)
{
        struct crypto_ctr_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 void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
                                   struct crypto_cipher *tfm)
{
        unsigned int bsize = crypto_cipher_blocksize(tfm);
        unsigned long alignmask = crypto_cipher_alignmask(tfm);
        u8 *ctrblk = walk->iv;
        u8 tmp[bsize + alignmask];
        u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
        u8 *src = walk->src.virt.addr;
        u8 *dst = walk->dst.virt.addr;
        unsigned int nbytes = walk->nbytes;

        crypto_cipher_encrypt_one(tfm, keystream, ctrblk);
        crypto_xor(keystream, src, nbytes);
        memcpy(dst, keystream, nbytes);

        crypto_inc(ctrblk, bsize);
}

static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
                                    struct crypto_cipher *tfm)
{
        void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
                   crypto_cipher_alg(tfm)->cia_encrypt;
        unsigned int bsize = crypto_cipher_blocksize(tfm);
        u8 *ctrblk = walk->iv;
        u8 *src = walk->src.virt.addr;
        u8 *dst = walk->dst.virt.addr;
        unsigned int nbytes = walk->nbytes;

        do {
                /* create keystream */
                fn(crypto_cipher_tfm(tfm), dst, ctrblk);
                crypto_xor(dst, src, bsize);

                /* increment counter in counterblock */
                crypto_inc(ctrblk, bsize);

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

        return nbytes;
}

static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
                                    struct crypto_cipher *tfm)
{
        void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
                   crypto_cipher_alg(tfm)->cia_encrypt;
        unsigned int bsize = crypto_cipher_blocksize(tfm);
        unsigned long alignmask = crypto_cipher_alignmask(tfm);
        unsigned int nbytes = walk->nbytes;
        u8 *ctrblk = walk->iv;
        u8 *src = walk->src.virt.addr;
        u8 tmp[bsize + alignmask];
        u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);

        do {
                /* create keystream */
                fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
                crypto_xor(src, keystream, bsize);

                /* increment counter in counterblock */
                crypto_inc(ctrblk, bsize);

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

        return nbytes;
}

static int crypto_ctr_crypt(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_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
        struct crypto_cipher *child = ctx->child;
        unsigned int bsize = crypto_cipher_blocksize(child);
        int err;

        blkcipher_walk_init(&walk, dst, src, nbytes);
        err = blkcipher_walk_virt_block(desc, &walk, bsize);

        while (walk.nbytes >= bsize) {
                if (walk.src.virt.addr == walk.dst.virt.addr)
                        nbytes = crypto_ctr_crypt_inplace(&walk, child);
                else
                        nbytes = crypto_ctr_crypt_segment(&walk, child);

                err = blkcipher_walk_done(desc, &walk, nbytes);
        }

        if (walk.nbytes) {
                crypto_ctr_crypt_final(&walk, child);
                err = blkcipher_walk_done(desc, &walk, 0);
        }

        return err;
}

static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
{
        struct crypto_instance *inst = (void *)tfm->__crt_alg;
        struct crypto_spawn *spawn = crypto_instance_ctx(inst);
        struct crypto_ctr_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_ctr_exit_tfm(struct crypto_tfm *tfm)
{
        struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);

        crypto_free_cipher(ctx->child);
}

static struct crypto_instance *crypto_ctr_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_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
                                  CRYPTO_ALG_TYPE_MASK);
        if (IS_ERR(alg))
                return ERR_PTR(PTR_ERR(alg));

        /* Block size must be >= 4 bytes. */
        err = -EINVAL;
        if (alg->cra_blocksize < 4)
                goto out_put_alg;

        /* If this is false we'd fail the alignment of crypto_inc. */
        if (alg->cra_blocksize % 4)
                goto out_put_alg;

        inst = crypto_alloc_instance("ctr", alg);
        if (IS_ERR(inst))
                goto out;

        inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
        inst->alg.cra_priority = alg->cra_priority;
        inst->alg.cra_blocksize = 1;
        inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1);
        inst->alg.cra_type = &crypto_blkcipher_type;

        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_ctr_ctx);

        inst->alg.cra_init = crypto_ctr_init_tfm;
        inst->alg.cra_exit = crypto_ctr_exit_tfm;

        inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
        inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
        inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;

out:
        crypto_mod_put(alg);
        return inst;

out_put_alg:
        inst = ERR_PTR(err);
        goto out;
}

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

static struct crypto_template crypto_ctr_tmpl = {
        .name = "ctr",
        .alloc = crypto_ctr_alloc,
        .free = crypto_ctr_free,
        .module = THIS_MODULE,
};

static int crypto_rfc3686_setkey(struct crypto_tfm *parent, const u8 *key,
                                 unsigned int keylen)
{
        struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(parent);
        struct crypto_blkcipher *child = ctx->child;
        int err;

        /* the nonce is stored in bytes at end of key */
        if (keylen < CTR_RFC3686_NONCE_SIZE)
                return -EINVAL;

        memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE),
               CTR_RFC3686_NONCE_SIZE);

        keylen -= CTR_RFC3686_NONCE_SIZE;

        crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
        crypto_blkcipher_set_flags(child, crypto_tfm_get_flags(parent) &
                                          CRYPTO_TFM_REQ_MASK);
        err = crypto_blkcipher_setkey(child, key, keylen);
        crypto_tfm_set_flags(parent, crypto_blkcipher_get_flags(child) &
                                     CRYPTO_TFM_RES_MASK);

        return err;
}

static int crypto_rfc3686_crypt(struct blkcipher_desc *desc,
                                struct scatterlist *dst,
                                struct scatterlist *src, unsigned int nbytes)
{
        struct crypto_blkcipher *tfm = desc->tfm;
        struct crypto_rfc3686_ctx *ctx = crypto_blkcipher_ctx(tfm);
        struct crypto_blkcipher *child = ctx->child;
        unsigned long alignmask = crypto_blkcipher_alignmask(tfm);
        u8 ivblk[CTR_RFC3686_BLOCK_SIZE + alignmask];
        u8 *iv = PTR_ALIGN(ivblk + 0, alignmask + 1);
        u8 *info = desc->info;
        int err;

        /* set up counter block */
        memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
        memcpy(iv + CTR_RFC3686_NONCE_SIZE, info, CTR_RFC3686_IV_SIZE);

        /* initialize counter portion of counter block */
        *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
                cpu_to_be32(1);

        desc->tfm = child;
        desc->info = iv;
        err = crypto_blkcipher_encrypt_iv(desc, dst, src, nbytes);
        desc->tfm = tfm;
        desc->info = info;

        return err;
}

static int crypto_rfc3686_init_tfm(struct crypto_tfm *tfm)
{
        struct crypto_instance *inst = (void *)tfm->__crt_alg;
        struct crypto_spawn *spawn = crypto_instance_ctx(inst);
        struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
        struct crypto_blkcipher *cipher;

        cipher = crypto_spawn_blkcipher(spawn);
        if (IS_ERR(cipher))
                return PTR_ERR(cipher);

        ctx->child = cipher;

        return 0;
}

static void crypto_rfc3686_exit_tfm(struct crypto_tfm *tfm)
{
        struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);

        crypto_free_blkcipher(ctx->child);
}

static struct crypto_instance *crypto_rfc3686_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_attr_alg(tb[1], CRYPTO_ALG_TYPE_BLKCIPHER,
                                  CRYPTO_ALG_TYPE_MASK);
        err = PTR_ERR(alg);
        if (IS_ERR(alg))
                return ERR_PTR(err);

        /* We only support 16-byte blocks. */
        err = -EINVAL;
        if (alg->cra_blkcipher.ivsize != CTR_RFC3686_BLOCK_SIZE)
                goto out_put_alg;

        /* Not a stream cipher? */
        if (alg->cra_blocksize != 1)
                goto out_put_alg;

        inst = crypto_alloc_instance("rfc3686", alg);
        if (IS_ERR(inst))
                goto out;

        inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
        inst->alg.cra_priority = alg->cra_priority;
        inst->alg.cra_blocksize = 1;
        inst->alg.cra_alignmask = alg->cra_alignmask;
        inst->alg.cra_type = &crypto_blkcipher_type;

        inst->alg.cra_blkcipher.ivsize = CTR_RFC3686_IV_SIZE;
        inst->alg.cra_blkcipher.min_keysize = alg->cra_blkcipher.min_keysize
                                              + CTR_RFC3686_NONCE_SIZE;
        inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize
                                              + CTR_RFC3686_NONCE_SIZE;

        inst->alg.cra_blkcipher.geniv = "seqiv";

        inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);

        inst->alg.cra_init = crypto_rfc3686_init_tfm;
        inst->alg.cra_exit = crypto_rfc3686_exit_tfm;

        inst->alg.cra_blkcipher.setkey = crypto_rfc3686_setkey;
        inst->alg.cra_blkcipher.encrypt = crypto_rfc3686_crypt;
        inst->alg.cra_blkcipher.decrypt = crypto_rfc3686_crypt;

out:
        crypto_mod_put(alg);
        return inst;

out_put_alg:
        inst = ERR_PTR(err);
        goto out;
}

static struct crypto_template crypto_rfc3686_tmpl = {
        .name = "rfc3686",
        .alloc = crypto_rfc3686_alloc,
        .free = crypto_ctr_free,
        .module = THIS_MODULE,
};

static int __init crypto_ctr_module_init(void)
{
        int err;

        err = crypto_register_template(&crypto_ctr_tmpl);
        if (err)
                goto out;

        err = crypto_register_template(&crypto_rfc3686_tmpl);
        if (err)
                goto out_drop_ctr;

out:
        return err;

out_drop_ctr:
        crypto_unregister_template(&crypto_ctr_tmpl);
        goto out;
}

static void __exit crypto_ctr_module_exit(void)
{
        crypto_unregister_template(&crypto_rfc3686_tmpl);
        crypto_unregister_template(&crypto_ctr_tmpl);
}

module_init(crypto_ctr_module_init);
module_exit(crypto_ctr_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("CTR Counter block mode");
MODULE_ALIAS("rfc3686");

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