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aes_s390.c

/*
 * Cryptographic API.
 *
 * s390 implementation of the AES Cipher Algorithm.
 *
 * s390 Version:
 *   Copyright IBM Corp. 2005,2007
 *   Author(s): Jan Glauber (jang@de.ibm.com)
 *          Sebastian Siewior (sebastian@breakpoint.cc> SW-Fallback
 *
 * Derived from "crypto/aes_generic.c"
 *
 * 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/aes.h>
#include <crypto/algapi.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include "crypt_s390.h"

#define AES_KEYLEN_128        1
#define AES_KEYLEN_192        2
#define AES_KEYLEN_256        4

static char keylen_flag = 0;

struct s390_aes_ctx {
      u8 iv[AES_BLOCK_SIZE];
      u8 key[AES_MAX_KEY_SIZE];
      long enc;
      long dec;
      int key_len;
      union {
            struct crypto_blkcipher *blk;
            struct crypto_cipher *cip;
      } fallback;
};

/*
 * Check if the key_len is supported by the HW.
 * Returns 0 if it is, a positive number if it is not and software fallback is
 * required or a negative number in case the key size is not valid
 */
static int need_fallback(unsigned int key_len)
{
      switch (key_len) {
      case 16:
            if (!(keylen_flag & AES_KEYLEN_128))
                  return 1;
            break;
      case 24:
            if (!(keylen_flag & AES_KEYLEN_192))
                  return 1;
            break;
      case 32:
            if (!(keylen_flag & AES_KEYLEN_256))
                  return 1;
            break;
      default:
            return -1;
            break;
      }
      return 0;
}

static int setkey_fallback_cip(struct crypto_tfm *tfm, const u8 *in_key,
            unsigned int key_len)
{
      struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);
      int ret;

      sctx->fallback.blk->base.crt_flags &= ~CRYPTO_TFM_REQ_MASK;
      sctx->fallback.blk->base.crt_flags |= (tfm->crt_flags &
                  CRYPTO_TFM_REQ_MASK);

      ret = crypto_cipher_setkey(sctx->fallback.cip, in_key, key_len);
      if (ret) {
            tfm->crt_flags &= ~CRYPTO_TFM_RES_MASK;
            tfm->crt_flags |= (sctx->fallback.blk->base.crt_flags &
                        CRYPTO_TFM_RES_MASK);
      }
      return ret;
}

static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
                   unsigned int key_len)
{
      struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);
      u32 *flags = &tfm->crt_flags;
      int ret;

      ret = need_fallback(key_len);
      if (ret < 0) {
            *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
            return -EINVAL;
      }

      sctx->key_len = key_len;
      if (!ret) {
            memcpy(sctx->key, in_key, key_len);
            return 0;
      }

      return setkey_fallback_cip(tfm, in_key, key_len);
}

static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
      const struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);

      if (unlikely(need_fallback(sctx->key_len))) {
            crypto_cipher_encrypt_one(sctx->fallback.cip, out, in);
            return;
      }

      switch (sctx->key_len) {
      case 16:
            crypt_s390_km(KM_AES_128_ENCRYPT, &sctx->key, out, in,
                        AES_BLOCK_SIZE);
            break;
      case 24:
            crypt_s390_km(KM_AES_192_ENCRYPT, &sctx->key, out, in,
                        AES_BLOCK_SIZE);
            break;
      case 32:
            crypt_s390_km(KM_AES_256_ENCRYPT, &sctx->key, out, in,
                        AES_BLOCK_SIZE);
            break;
      }
}

static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
      const struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);

      if (unlikely(need_fallback(sctx->key_len))) {
            crypto_cipher_decrypt_one(sctx->fallback.cip, out, in);
            return;
      }

      switch (sctx->key_len) {
      case 16:
            crypt_s390_km(KM_AES_128_DECRYPT, &sctx->key, out, in,
                        AES_BLOCK_SIZE);
            break;
      case 24:
            crypt_s390_km(KM_AES_192_DECRYPT, &sctx->key, out, in,
                        AES_BLOCK_SIZE);
            break;
      case 32:
            crypt_s390_km(KM_AES_256_DECRYPT, &sctx->key, out, in,
                        AES_BLOCK_SIZE);
            break;
      }
}

static int fallback_init_cip(struct crypto_tfm *tfm)
{
      const char *name = tfm->__crt_alg->cra_name;
      struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);

      sctx->fallback.cip = crypto_alloc_cipher(name, 0,
                  CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK);

      if (IS_ERR(sctx->fallback.cip)) {
            printk(KERN_ERR "Error allocating fallback algo %s\n", name);
            return PTR_ERR(sctx->fallback.blk);
      }

      return 0;
}

static void fallback_exit_cip(struct crypto_tfm *tfm)
{
      struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);

      crypto_free_cipher(sctx->fallback.cip);
      sctx->fallback.cip = NULL;
}

static struct crypto_alg aes_alg = {
      .cra_name         =     "aes",
      .cra_driver_name  =     "aes-s390",
      .cra_priority           =     CRYPT_S390_PRIORITY,
      .cra_flags        =     CRYPTO_ALG_TYPE_CIPHER |
                              CRYPTO_ALG_NEED_FALLBACK,
      .cra_blocksize          =     AES_BLOCK_SIZE,
      .cra_ctxsize            =     sizeof(struct s390_aes_ctx),
      .cra_module       =     THIS_MODULE,
      .cra_list         =     LIST_HEAD_INIT(aes_alg.cra_list),
      .cra_init               =       fallback_init_cip,
      .cra_exit               =       fallback_exit_cip,
      .cra_u                  =     {
            .cipher = {
                  .cia_min_keysize  =     AES_MIN_KEY_SIZE,
                  .cia_max_keysize  =     AES_MAX_KEY_SIZE,
                  .cia_setkey       =     aes_set_key,
                  .cia_encrypt            =     aes_encrypt,
                  .cia_decrypt            =     aes_decrypt,
            }
      }
};

static int setkey_fallback_blk(struct crypto_tfm *tfm, const u8 *key,
            unsigned int len)
{
      struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);
      unsigned int ret;

      sctx->fallback.blk->base.crt_flags &= ~CRYPTO_TFM_REQ_MASK;
      sctx->fallback.blk->base.crt_flags |= (tfm->crt_flags &
                  CRYPTO_TFM_REQ_MASK);

      ret = crypto_blkcipher_setkey(sctx->fallback.blk, key, len);
      if (ret) {
            tfm->crt_flags &= ~CRYPTO_TFM_RES_MASK;
            tfm->crt_flags |= (sctx->fallback.blk->base.crt_flags &
                        CRYPTO_TFM_RES_MASK);
      }
      return ret;
}

static int fallback_blk_dec(struct blkcipher_desc *desc,
            struct scatterlist *dst, struct scatterlist *src,
            unsigned int nbytes)
{
      unsigned int ret;
      struct crypto_blkcipher *tfm;
      struct s390_aes_ctx *sctx = crypto_blkcipher_ctx(desc->tfm);

      tfm = desc->tfm;
      desc->tfm = sctx->fallback.blk;

      ret = crypto_blkcipher_decrypt_iv(desc, dst, src, nbytes);

      desc->tfm = tfm;
      return ret;
}

static int fallback_blk_enc(struct blkcipher_desc *desc,
            struct scatterlist *dst, struct scatterlist *src,
            unsigned int nbytes)
{
      unsigned int ret;
      struct crypto_blkcipher *tfm;
      struct s390_aes_ctx *sctx = crypto_blkcipher_ctx(desc->tfm);

      tfm = desc->tfm;
      desc->tfm = sctx->fallback.blk;

      ret = crypto_blkcipher_encrypt_iv(desc, dst, src, nbytes);

      desc->tfm = tfm;
      return ret;
}

static int ecb_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
                     unsigned int key_len)
{
      struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);
      int ret;

      ret = need_fallback(key_len);
      if (ret > 0) {
            sctx->key_len = key_len;
            return setkey_fallback_blk(tfm, in_key, key_len);
      }

      switch (key_len) {
      case 16:
            sctx->enc = KM_AES_128_ENCRYPT;
            sctx->dec = KM_AES_128_DECRYPT;
            break;
      case 24:
            sctx->enc = KM_AES_192_ENCRYPT;
            sctx->dec = KM_AES_192_DECRYPT;
            break;
      case 32:
            sctx->enc = KM_AES_256_ENCRYPT;
            sctx->dec = KM_AES_256_DECRYPT;
            break;
      }

      return aes_set_key(tfm, in_key, key_len);
}

static int ecb_aes_crypt(struct blkcipher_desc *desc, long func, void *param,
                   struct blkcipher_walk *walk)
{
      int ret = blkcipher_walk_virt(desc, walk);
      unsigned int nbytes;

      while ((nbytes = walk->nbytes)) {
            /* only use complete blocks */
            unsigned int n = nbytes & ~(AES_BLOCK_SIZE - 1);
            u8 *out = walk->dst.virt.addr;
            u8 *in = walk->src.virt.addr;

            ret = crypt_s390_km(func, param, out, in, n);
            BUG_ON((ret < 0) || (ret != n));

            nbytes &= AES_BLOCK_SIZE - 1;
            ret = blkcipher_walk_done(desc, walk, nbytes);
      }

      return ret;
}

static int ecb_aes_encrypt(struct blkcipher_desc *desc,
                     struct scatterlist *dst, struct scatterlist *src,
                     unsigned int nbytes)
{
      struct s390_aes_ctx *sctx = crypto_blkcipher_ctx(desc->tfm);
      struct blkcipher_walk walk;

      if (unlikely(need_fallback(sctx->key_len)))
            return fallback_blk_enc(desc, dst, src, nbytes);

      blkcipher_walk_init(&walk, dst, src, nbytes);
      return ecb_aes_crypt(desc, sctx->enc, sctx->key, &walk);
}

static int ecb_aes_decrypt(struct blkcipher_desc *desc,
                     struct scatterlist *dst, struct scatterlist *src,
                     unsigned int nbytes)
{
      struct s390_aes_ctx *sctx = crypto_blkcipher_ctx(desc->tfm);
      struct blkcipher_walk walk;

      if (unlikely(need_fallback(sctx->key_len)))
            return fallback_blk_dec(desc, dst, src, nbytes);

      blkcipher_walk_init(&walk, dst, src, nbytes);
      return ecb_aes_crypt(desc, sctx->dec, sctx->key, &walk);
}

static int fallback_init_blk(struct crypto_tfm *tfm)
{
      const char *name = tfm->__crt_alg->cra_name;
      struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);

      sctx->fallback.blk = crypto_alloc_blkcipher(name, 0,
                  CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK);

      if (IS_ERR(sctx->fallback.blk)) {
            printk(KERN_ERR "Error allocating fallback algo %s\n", name);
            return PTR_ERR(sctx->fallback.blk);
      }

      return 0;
}

static void fallback_exit_blk(struct crypto_tfm *tfm)
{
      struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);

      crypto_free_blkcipher(sctx->fallback.blk);
      sctx->fallback.blk = NULL;
}

static struct crypto_alg ecb_aes_alg = {
      .cra_name         =     "ecb(aes)",
      .cra_driver_name  =     "ecb-aes-s390",
      .cra_priority           =     CRYPT_S390_COMPOSITE_PRIORITY,
      .cra_flags        =     CRYPTO_ALG_TYPE_BLKCIPHER |
                              CRYPTO_ALG_NEED_FALLBACK,
      .cra_blocksize          =     AES_BLOCK_SIZE,
      .cra_ctxsize            =     sizeof(struct s390_aes_ctx),
      .cra_type         =     &crypto_blkcipher_type,
      .cra_module       =     THIS_MODULE,
      .cra_list         =     LIST_HEAD_INIT(ecb_aes_alg.cra_list),
      .cra_init         =     fallback_init_blk,
      .cra_exit         =     fallback_exit_blk,
      .cra_u                  =     {
            .blkcipher = {
                  .min_keysize            =     AES_MIN_KEY_SIZE,
                  .max_keysize            =     AES_MAX_KEY_SIZE,
                  .setkey                 =     ecb_aes_set_key,
                  .encrypt          =     ecb_aes_encrypt,
                  .decrypt          =     ecb_aes_decrypt,
            }
      }
};

static int cbc_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
                     unsigned int key_len)
{
      struct s390_aes_ctx *sctx = crypto_tfm_ctx(tfm);
      int ret;

      ret = need_fallback(key_len);
      if (ret > 0) {
            sctx->key_len = key_len;
            return setkey_fallback_blk(tfm, in_key, key_len);
      }

      switch (key_len) {
      case 16:
            sctx->enc = KMC_AES_128_ENCRYPT;
            sctx->dec = KMC_AES_128_DECRYPT;
            break;
      case 24:
            sctx->enc = KMC_AES_192_ENCRYPT;
            sctx->dec = KMC_AES_192_DECRYPT;
            break;
      case 32:
            sctx->enc = KMC_AES_256_ENCRYPT;
            sctx->dec = KMC_AES_256_DECRYPT;
            break;
      }

      return aes_set_key(tfm, in_key, key_len);
}

static int cbc_aes_crypt(struct blkcipher_desc *desc, long func, void *param,
                   struct blkcipher_walk *walk)
{
      int ret = blkcipher_walk_virt(desc, walk);
      unsigned int nbytes = walk->nbytes;

      if (!nbytes)
            goto out;

      memcpy(param, walk->iv, AES_BLOCK_SIZE);
      do {
            /* only use complete blocks */
            unsigned int n = nbytes & ~(AES_BLOCK_SIZE - 1);
            u8 *out = walk->dst.virt.addr;
            u8 *in = walk->src.virt.addr;

            ret = crypt_s390_kmc(func, param, out, in, n);
            BUG_ON((ret < 0) || (ret != n));

            nbytes &= AES_BLOCK_SIZE - 1;
            ret = blkcipher_walk_done(desc, walk, nbytes);
      } while ((nbytes = walk->nbytes));
      memcpy(walk->iv, param, AES_BLOCK_SIZE);

out:
      return ret;
}

static int cbc_aes_encrypt(struct blkcipher_desc *desc,
                     struct scatterlist *dst, struct scatterlist *src,
                     unsigned int nbytes)
{
      struct s390_aes_ctx *sctx = crypto_blkcipher_ctx(desc->tfm);
      struct blkcipher_walk walk;

      if (unlikely(need_fallback(sctx->key_len)))
            return fallback_blk_enc(desc, dst, src, nbytes);

      blkcipher_walk_init(&walk, dst, src, nbytes);
      return cbc_aes_crypt(desc, sctx->enc, sctx->iv, &walk);
}

static int cbc_aes_decrypt(struct blkcipher_desc *desc,
                     struct scatterlist *dst, struct scatterlist *src,
                     unsigned int nbytes)
{
      struct s390_aes_ctx *sctx = crypto_blkcipher_ctx(desc->tfm);
      struct blkcipher_walk walk;

      if (unlikely(need_fallback(sctx->key_len)))
            return fallback_blk_dec(desc, dst, src, nbytes);

      blkcipher_walk_init(&walk, dst, src, nbytes);
      return cbc_aes_crypt(desc, sctx->dec, sctx->iv, &walk);
}

static struct crypto_alg cbc_aes_alg = {
      .cra_name         =     "cbc(aes)",
      .cra_driver_name  =     "cbc-aes-s390",
      .cra_priority           =     CRYPT_S390_COMPOSITE_PRIORITY,
      .cra_flags        =     CRYPTO_ALG_TYPE_BLKCIPHER |
                              CRYPTO_ALG_NEED_FALLBACK,
      .cra_blocksize          =     AES_BLOCK_SIZE,
      .cra_ctxsize            =     sizeof(struct s390_aes_ctx),
      .cra_type         =     &crypto_blkcipher_type,
      .cra_module       =     THIS_MODULE,
      .cra_list         =     LIST_HEAD_INIT(cbc_aes_alg.cra_list),
      .cra_init         =     fallback_init_blk,
      .cra_exit         =     fallback_exit_blk,
      .cra_u                  =     {
            .blkcipher = {
                  .min_keysize            =     AES_MIN_KEY_SIZE,
                  .max_keysize            =     AES_MAX_KEY_SIZE,
                  .ivsize                 =     AES_BLOCK_SIZE,
                  .setkey                 =     cbc_aes_set_key,
                  .encrypt          =     cbc_aes_encrypt,
                  .decrypt          =     cbc_aes_decrypt,
            }
      }
};

static int __init aes_s390_init(void)
{
      int ret;

      if (crypt_s390_func_available(KM_AES_128_ENCRYPT))
            keylen_flag |= AES_KEYLEN_128;
      if (crypt_s390_func_available(KM_AES_192_ENCRYPT))
            keylen_flag |= AES_KEYLEN_192;
      if (crypt_s390_func_available(KM_AES_256_ENCRYPT))
            keylen_flag |= AES_KEYLEN_256;

      if (!keylen_flag)
            return -EOPNOTSUPP;

      /* z9 109 and z9 BC/EC only support 128 bit key length */
      if (keylen_flag == AES_KEYLEN_128)
            printk(KERN_INFO
                   "aes_s390: hardware acceleration only available for "
                   "128 bit keys\n");

      ret = crypto_register_alg(&aes_alg);
      if (ret)
            goto aes_err;

      ret = crypto_register_alg(&ecb_aes_alg);
      if (ret)
            goto ecb_aes_err;

      ret = crypto_register_alg(&cbc_aes_alg);
      if (ret)
            goto cbc_aes_err;

out:
      return ret;

cbc_aes_err:
      crypto_unregister_alg(&ecb_aes_alg);
ecb_aes_err:
      crypto_unregister_alg(&aes_alg);
aes_err:
      goto out;
}

static void __exit aes_s390_fini(void)
{
      crypto_unregister_alg(&cbc_aes_alg);
      crypto_unregister_alg(&ecb_aes_alg);
      crypto_unregister_alg(&aes_alg);
}

module_init(aes_s390_init);
module_exit(aes_s390_fini);

MODULE_ALIAS("aes");

MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm");
MODULE_LICENSE("GPL");

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