/*
   * CCM: Counter with CBC-MAC
   *
   * (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/internal/aead.h>
  #include <crypto/internal/skcipher.h>
  #include <crypto/scatterwalk.h>
  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  
  #include "internal.h"
  
  struct ccm_instance_ctx {
  	struct crypto_skcipher_spawn ctr;
  	struct crypto_spawn cipher;
  };
  
  struct crypto_ccm_ctx {
  	struct crypto_cipher *cipher;

  	struct crypto_skcipher *ctr;

  };
  
  struct crypto_rfc4309_ctx {
  	struct crypto_aead *child;
  	u8 nonce[3];
  };

  struct crypto_rfc4309_req_ctx {
  	struct scatterlist src[3];
  	struct scatterlist dst[3];
  	struct aead_request subreq;
  };

  struct crypto_ccm_req_priv_ctx {
  	u8 odata[16];
  	u8 idata[16];
  	u8 auth_tag[16];
  	u32 ilen;
  	u32 flags;

  	struct scatterlist src[3];
  	struct scatterlist dst[3];

  	struct skcipher_request skreq;

  };
  
  static inline struct crypto_ccm_req_priv_ctx *crypto_ccm_reqctx(
  	struct aead_request *req)
  {
  	unsigned long align = crypto_aead_alignmask(crypto_aead_reqtfm(req));
  
  	return (void *)PTR_ALIGN((u8 *)aead_request_ctx(req), align + 1);
  }
  
  static int set_msg_len(u8 *block, unsigned int msglen, int csize)
  {
  	__be32 data;
  
  	memset(block, 0, csize);
  	block += csize;
  
  	if (csize >= 4)
  		csize = 4;
  	else if (msglen > (1 << (8 * csize)))
  		return -EOVERFLOW;
  
  	data = cpu_to_be32(msglen);
  	memcpy(block - csize, (u8 *)&data + 4 - csize, csize);
  
  	return 0;
  }
  
  static int crypto_ccm_setkey(struct crypto_aead *aead, const u8 *key,
  			     unsigned int keylen)
  {
  	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);

  	struct crypto_skcipher *ctr = ctx->ctr;

  	struct crypto_cipher *tfm = ctx->cipher;
  	int err = 0;

  	crypto_skcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK);
  	crypto_skcipher_set_flags(ctr, crypto_aead_get_flags(aead) &
  				       CRYPTO_TFM_REQ_MASK);
  	err = crypto_skcipher_setkey(ctr, key, keylen);
  	crypto_aead_set_flags(aead, crypto_skcipher_get_flags(ctr) &

  			      CRYPTO_TFM_RES_MASK);
  	if (err)
  		goto out;
  
  	crypto_cipher_clear_flags(tfm, CRYPTO_TFM_REQ_MASK);
  	crypto_cipher_set_flags(tfm, crypto_aead_get_flags(aead) &
  				    CRYPTO_TFM_REQ_MASK);
  	err = crypto_cipher_setkey(tfm, key, keylen);
  	crypto_aead_set_flags(aead, crypto_cipher_get_flags(tfm) &
  			      CRYPTO_TFM_RES_MASK);
  
  out:
  	return err;
  }
  
  static int crypto_ccm_setauthsize(struct crypto_aead *tfm,
  				  unsigned int authsize)
  {
  	switch (authsize) {
  	case 4:
  	case 6:
  	case 8:
  	case 10:
  	case 12:
  	case 14:
  	case 16:
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static int format_input(u8 *info, struct aead_request *req,
  			unsigned int cryptlen)
  {
  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	unsigned int lp = req->iv[0];
  	unsigned int l = lp + 1;
  	unsigned int m;
  
  	m = crypto_aead_authsize(aead);
  
  	memcpy(info, req->iv, 16);
  
  	/* format control info per RFC 3610 and
  	 * NIST Special Publication 800-38C
  	 */
  	*info |= (8 * ((m - 2) / 2));
  	if (req->assoclen)
  		*info |= 64;
  
  	return set_msg_len(info + 16 - l, cryptlen, l);
  }
  
  static int format_adata(u8 *adata, unsigned int a)
  {
  	int len = 0;
  
  	/* add control info for associated data
  	 * RFC 3610 and NIST Special Publication 800-38C
  	 */
  	if (a < 65280) {
  		*(__be16 *)adata = cpu_to_be16(a);
  		len = 2;
  	} else  {
  		*(__be16 *)adata = cpu_to_be16(0xfffe);
  		*(__be32 *)&adata[2] = cpu_to_be32(a);
  		len = 6;
  	}
  
  	return len;
  }
  
  static void compute_mac(struct crypto_cipher *tfm, u8 *data, int n,
  		       struct crypto_ccm_req_priv_ctx *pctx)
  {
  	unsigned int bs = 16;
  	u8 *odata = pctx->odata;
  	u8 *idata = pctx->idata;
  	int datalen, getlen;
  
  	datalen = n;
  
  	/* first time in here, block may be partially filled. */
  	getlen = bs - pctx->ilen;
  	if (datalen >= getlen) {
  		memcpy(idata + pctx->ilen, data, getlen);
  		crypto_xor(odata, idata, bs);
  		crypto_cipher_encrypt_one(tfm, odata, odata);
  		datalen -= getlen;
  		data += getlen;
  		pctx->ilen = 0;
  	}
  
  	/* now encrypt rest of data */
  	while (datalen >= bs) {
  		crypto_xor(odata, data, bs);
  		crypto_cipher_encrypt_one(tfm, odata, odata);
  
  		datalen -= bs;
  		data += bs;
  	}
  
  	/* check and see if there's leftover data that wasn't
  	 * enough to fill a block.
  	 */
  	if (datalen) {
  		memcpy(idata + pctx->ilen, data, datalen);
  		pctx->ilen += datalen;
  	}
  }
  
  static void get_data_to_compute(struct crypto_cipher *tfm,
  			       struct crypto_ccm_req_priv_ctx *pctx,
  			       struct scatterlist *sg, unsigned int len)
  {
  	struct scatter_walk walk;
  	u8 *data_src;
  	int n;
  
  	scatterwalk_start(&walk, sg);
  
  	while (len) {
  		n = scatterwalk_clamp(&walk, len);
  		if (!n) {
  			scatterwalk_start(&walk, sg_next(walk.sg));
  			n = scatterwalk_clamp(&walk, len);
  		}

  		data_src = scatterwalk_map(&walk);

  
  		compute_mac(tfm, data_src, n, pctx);
  		len -= n;

  		scatterwalk_unmap(data_src);

  		scatterwalk_advance(&walk, n);
  		scatterwalk_done(&walk, 0, len);
  		if (len)
  			crypto_yield(pctx->flags);
  	}
  
  	/* any leftover needs padding and then encrypted */
  	if (pctx->ilen) {
  		int padlen;
  		u8 *odata = pctx->odata;
  		u8 *idata = pctx->idata;
  
  		padlen = 16 - pctx->ilen;
  		memset(idata + pctx->ilen, 0, padlen);
  		crypto_xor(odata, idata, 16);
  		crypto_cipher_encrypt_one(tfm, odata, odata);
  		pctx->ilen = 0;
  	}
  }
  
  static int crypto_ccm_auth(struct aead_request *req, struct scatterlist *plain,
  			   unsigned int cryptlen)
  {
  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
  	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
  	struct crypto_cipher *cipher = ctx->cipher;
  	unsigned int assoclen = req->assoclen;
  	u8 *odata = pctx->odata;
  	u8 *idata = pctx->idata;
  	int err;
  
  	/* format control data for input */
  	err = format_input(odata, req, cryptlen);
  	if (err)
  		goto out;
  
  	/* encrypt first block to use as start in computing mac  */
  	crypto_cipher_encrypt_one(cipher, odata, odata);
  
  	/* format associated data and compute into mac */
  	if (assoclen) {
  		pctx->ilen = format_adata(idata, assoclen);

  		get_data_to_compute(cipher, pctx, req->src, req->assoclen);

  	} else {
  		pctx->ilen = 0;

  	}
  
  	/* compute plaintext into mac */

  	if (cryptlen)
  		get_data_to_compute(cipher, pctx, plain, cryptlen);

  
  out:
  	return err;
  }
  
  static void crypto_ccm_encrypt_done(struct crypto_async_request *areq, int err)
  {
  	struct aead_request *req = areq->data;
  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
  	u8 *odata = pctx->odata;
  
  	if (!err)

  		scatterwalk_map_and_copy(odata, req->dst,
  					 req->assoclen + req->cryptlen,

  					 crypto_aead_authsize(aead), 1);
  	aead_request_complete(req, err);
  }
  
  static inline int crypto_ccm_check_iv(const u8 *iv)
  {
  	/* 2 <= L <= 8, so 1 <= L' <= 7. */
  	if (1 > iv[0] || iv[0] > 7)
  		return -EINVAL;
  
  	return 0;
  }

  static int crypto_ccm_init_crypt(struct aead_request *req, u8 *tag)
  {
  	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
  	struct scatterlist *sg;
  	u8 *iv = req->iv;
  	int err;
  
  	err = crypto_ccm_check_iv(iv);
  	if (err)
  		return err;
  
  	pctx->flags = aead_request_flags(req);
  
  	 /* Note: rfc 3610 and NIST 800-38C require counter of
  	 * zero to encrypt auth tag.
  	 */
  	memset(iv + 15 - iv[0], 0, iv[0] + 1);
  
  	sg_init_table(pctx->src, 3);
  	sg_set_buf(pctx->src, tag, 16);
  	sg = scatterwalk_ffwd(pctx->src + 1, req->src, req->assoclen);
  	if (sg != pctx->src + 1)
  		sg_chain(pctx->src, 2, sg);
  
  	if (req->src != req->dst) {
  		sg_init_table(pctx->dst, 3);
  		sg_set_buf(pctx->dst, tag, 16);
  		sg = scatterwalk_ffwd(pctx->dst + 1, req->dst, req->assoclen);
  		if (sg != pctx->dst + 1)
  			sg_chain(pctx->dst, 2, sg);
  	}
  
  	return 0;
  }

  static int crypto_ccm_encrypt(struct aead_request *req)
  {
  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
  	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);

  	struct skcipher_request *skreq = &pctx->skreq;

  	struct scatterlist *dst;
  	unsigned int cryptlen = req->cryptlen;
  	u8 *odata = pctx->odata;
  	u8 *iv = req->iv;
  	int err;

  	err = crypto_ccm_init_crypt(req, odata);

  	if (err)
  		return err;

  	err = crypto_ccm_auth(req, sg_next(pctx->src), cryptlen);

  	if (err)
  		return err;

  	dst = pctx->src;

  	if (req->src != req->dst)

  		dst = pctx->dst;

  	skcipher_request_set_tfm(skreq, ctx->ctr);
  	skcipher_request_set_callback(skreq, pctx->flags,
  				      crypto_ccm_encrypt_done, req);
  	skcipher_request_set_crypt(skreq, pctx->src, dst, cryptlen + 16, iv);
  	err = crypto_skcipher_encrypt(skreq);

  	if (err)
  		return err;
  
  	/* copy authtag to end of dst */

  	scatterwalk_map_and_copy(odata, sg_next(dst), cryptlen,

  				 crypto_aead_authsize(aead), 1);
  	return err;
  }
  
  static void crypto_ccm_decrypt_done(struct crypto_async_request *areq,
  				   int err)
  {
  	struct aead_request *req = areq->data;
  	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	unsigned int authsize = crypto_aead_authsize(aead);
  	unsigned int cryptlen = req->cryptlen - authsize;

  	struct scatterlist *dst;
  
  	pctx->flags = 0;
  
  	dst = sg_next(req->src == req->dst ? pctx->src : pctx->dst);

  
  	if (!err) {

  		err = crypto_ccm_auth(req, dst, cryptlen);

  		if (!err && crypto_memneq(pctx->auth_tag, pctx->odata, authsize))

  			err = -EBADMSG;
  	}
  	aead_request_complete(req, err);
  }
  
  static int crypto_ccm_decrypt(struct aead_request *req)
  {
  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
  	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);

  	struct skcipher_request *skreq = &pctx->skreq;

  	struct scatterlist *dst;
  	unsigned int authsize = crypto_aead_authsize(aead);
  	unsigned int cryptlen = req->cryptlen;
  	u8 *authtag = pctx->auth_tag;
  	u8 *odata = pctx->odata;
  	u8 *iv = req->iv;
  	int err;

  	cryptlen -= authsize;

  	err = crypto_ccm_init_crypt(req, authtag);

  	if (err)
  		return err;

  	scatterwalk_map_and_copy(authtag, sg_next(pctx->src), cryptlen,
  				 authsize, 0);

  
  	dst = pctx->src;

  	if (req->src != req->dst)

  		dst = pctx->dst;

  	skcipher_request_set_tfm(skreq, ctx->ctr);
  	skcipher_request_set_callback(skreq, pctx->flags,
  				      crypto_ccm_decrypt_done, req);
  	skcipher_request_set_crypt(skreq, pctx->src, dst, cryptlen + 16, iv);
  	err = crypto_skcipher_decrypt(skreq);

  	if (err)
  		return err;

  	err = crypto_ccm_auth(req, sg_next(dst), cryptlen);

  	if (err)
  		return err;
  
  	/* verify */

  	if (crypto_memneq(authtag, odata, authsize))

  		return -EBADMSG;
  
  	return err;
  }

  static int crypto_ccm_init_tfm(struct crypto_aead *tfm)

  {

  	struct aead_instance *inst = aead_alg_instance(tfm);
  	struct ccm_instance_ctx *ictx = aead_instance_ctx(inst);
  	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(tfm);

  	struct crypto_cipher *cipher;

  	struct crypto_skcipher *ctr;

  	unsigned long align;
  	int err;
  
  	cipher = crypto_spawn_cipher(&ictx->cipher);
  	if (IS_ERR(cipher))
  		return PTR_ERR(cipher);

  	ctr = crypto_spawn_skcipher2(&ictx->ctr);

  	err = PTR_ERR(ctr);
  	if (IS_ERR(ctr))
  		goto err_free_cipher;
  
  	ctx->cipher = cipher;
  	ctx->ctr = ctr;

  	align = crypto_aead_alignmask(tfm);

  	align &= ~(crypto_tfm_ctx_alignment() - 1);

  	crypto_aead_set_reqsize(
  		tfm,

  		align + sizeof(struct crypto_ccm_req_priv_ctx) +

  		crypto_skcipher_reqsize(ctr));

  
  	return 0;
  
  err_free_cipher:
  	crypto_free_cipher(cipher);
  	return err;
  }

  static void crypto_ccm_exit_tfm(struct crypto_aead *tfm)

  {

  	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(tfm);

  
  	crypto_free_cipher(ctx->cipher);

  	crypto_free_skcipher(ctx->ctr);

  }

  static void crypto_ccm_free(struct aead_instance *inst)
  {
  	struct ccm_instance_ctx *ctx = aead_instance_ctx(inst);
  
  	crypto_drop_spawn(&ctx->cipher);
  	crypto_drop_skcipher(&ctx->ctr);
  	kfree(inst);
  }
  
  static int crypto_ccm_create_common(struct crypto_template *tmpl,
  				    struct rtattr **tb,
  				    const char *full_name,
  				    const char *ctr_name,
  				    const char *cipher_name)

  {
  	struct crypto_attr_type *algt;

  	struct aead_instance *inst;

  	struct skcipher_alg *ctr;

  	struct crypto_alg *cipher;
  	struct ccm_instance_ctx *ictx;
  	int err;
  
  	algt = crypto_get_attr_type(tb);

  	if (IS_ERR(algt))

  		return PTR_ERR(algt);

  	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)

  		return -EINVAL;

  
  	cipher = crypto_alg_mod_lookup(cipher_name,  CRYPTO_ALG_TYPE_CIPHER,
  				       CRYPTO_ALG_TYPE_MASK);

  	if (IS_ERR(cipher))

  		return PTR_ERR(cipher);

  
  	err = -EINVAL;
  	if (cipher->cra_blocksize != 16)
  		goto out_put_cipher;
  
  	inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
  	err = -ENOMEM;
  	if (!inst)
  		goto out_put_cipher;

  	ictx = aead_instance_ctx(inst);

  	err = crypto_init_spawn(&ictx->cipher, cipher,
  				aead_crypto_instance(inst),

  				CRYPTO_ALG_TYPE_MASK);
  	if (err)
  		goto err_free_inst;

  	crypto_set_skcipher_spawn(&ictx->ctr, aead_crypto_instance(inst));

  	err = crypto_grab_skcipher2(&ictx->ctr, ctr_name, 0,
  				    crypto_requires_sync(algt->type,
  							 algt->mask));

  	if (err)
  		goto err_drop_cipher;

  	ctr = crypto_spawn_skcipher_alg(&ictx->ctr);

  
  	/* Not a stream cipher? */
  	err = -EINVAL;

  	if (ctr->base.cra_blocksize != 1)

  		goto err_drop_ctr;
  
  	/* We want the real thing! */

  	if (crypto_skcipher_alg_ivsize(ctr) != 16)

  		goto err_drop_ctr;
  
  	err = -ENAMETOOLONG;

  	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,

  		     "ccm_base(%s,%s)", ctr->base.cra_driver_name,

  		     cipher->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
  		goto err_drop_ctr;

  	memcpy(inst->alg.base.cra_name, full_name, CRYPTO_MAX_ALG_NAME);

  	inst->alg.base.cra_flags = ctr->base.cra_flags & CRYPTO_ALG_ASYNC;

  	inst->alg.base.cra_priority = (cipher->cra_priority +

  				       ctr->base.cra_priority) / 2;

  	inst->alg.base.cra_blocksize = 1;
  	inst->alg.base.cra_alignmask = cipher->cra_alignmask |

  				       ctr->base.cra_alignmask |

  				       (__alignof__(u32) - 1);
  	inst->alg.ivsize = 16;

  	inst->alg.chunksize = crypto_skcipher_alg_chunksize(ctr);

  	inst->alg.maxauthsize = 16;
  	inst->alg.base.cra_ctxsize = sizeof(struct crypto_ccm_ctx);
  	inst->alg.init = crypto_ccm_init_tfm;
  	inst->alg.exit = crypto_ccm_exit_tfm;
  	inst->alg.setkey = crypto_ccm_setkey;
  	inst->alg.setauthsize = crypto_ccm_setauthsize;
  	inst->alg.encrypt = crypto_ccm_encrypt;
  	inst->alg.decrypt = crypto_ccm_decrypt;
  
  	inst->free = crypto_ccm_free;
  
  	err = aead_register_instance(tmpl, inst);
  	if (err)
  		goto err_drop_ctr;

  out_put_cipher:

  	crypto_mod_put(cipher);

  	return err;

  
  err_drop_ctr:
  	crypto_drop_skcipher(&ictx->ctr);
  err_drop_cipher:
  	crypto_drop_spawn(&ictx->cipher);
  err_free_inst:
  	kfree(inst);

  	goto out_put_cipher;

  }

  static int crypto_ccm_create(struct crypto_template *tmpl, struct rtattr **tb)

  {

  	const char *cipher_name;
  	char ctr_name[CRYPTO_MAX_ALG_NAME];
  	char full_name[CRYPTO_MAX_ALG_NAME];
  
  	cipher_name = crypto_attr_alg_name(tb[1]);

  	if (IS_ERR(cipher_name))

  		return PTR_ERR(cipher_name);

  
  	if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
  		     cipher_name) >= CRYPTO_MAX_ALG_NAME)

  		return -ENAMETOOLONG;

  
  	if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "ccm(%s)", cipher_name) >=
  	    CRYPTO_MAX_ALG_NAME)

  		return -ENAMETOOLONG;

  	return crypto_ccm_create_common(tmpl, tb, full_name, ctr_name,
  					cipher_name);

  }
  
  static struct crypto_template crypto_ccm_tmpl = {
  	.name = "ccm",

  	.create = crypto_ccm_create,

  	.module = THIS_MODULE,
  };

  static int crypto_ccm_base_create(struct crypto_template *tmpl,
  				  struct rtattr **tb)

  {

  	const char *ctr_name;
  	const char *cipher_name;
  	char full_name[CRYPTO_MAX_ALG_NAME];
  
  	ctr_name = crypto_attr_alg_name(tb[1]);

  	if (IS_ERR(ctr_name))

  		return PTR_ERR(ctr_name);

  
  	cipher_name = crypto_attr_alg_name(tb[2]);

  	if (IS_ERR(cipher_name))

  		return PTR_ERR(cipher_name);

  
  	if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "ccm_base(%s,%s)",
  		     ctr_name, cipher_name) >= CRYPTO_MAX_ALG_NAME)

  		return -ENAMETOOLONG;

  	return crypto_ccm_create_common(tmpl, tb, full_name, ctr_name,
  					cipher_name);

  }
  
  static struct crypto_template crypto_ccm_base_tmpl = {
  	.name = "ccm_base",

  	.create = crypto_ccm_base_create,

  	.module = THIS_MODULE,
  };
  
  static int crypto_rfc4309_setkey(struct crypto_aead *parent, const u8 *key,
  				 unsigned int keylen)
  {
  	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(parent);
  	struct crypto_aead *child = ctx->child;
  	int err;
  
  	if (keylen < 3)
  		return -EINVAL;
  
  	keylen -= 3;
  	memcpy(ctx->nonce, key + keylen, 3);
  
  	crypto_aead_clear_flags(child, CRYPTO_TFM_REQ_MASK);
  	crypto_aead_set_flags(child, crypto_aead_get_flags(parent) &
  				     CRYPTO_TFM_REQ_MASK);
  	err = crypto_aead_setkey(child, key, keylen);
  	crypto_aead_set_flags(parent, crypto_aead_get_flags(child) &
  				      CRYPTO_TFM_RES_MASK);
  
  	return err;
  }
  
  static int crypto_rfc4309_setauthsize(struct crypto_aead *parent,
  				      unsigned int authsize)
  {
  	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(parent);
  
  	switch (authsize) {
  	case 8:
  	case 12:
  	case 16:
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	return crypto_aead_setauthsize(ctx->child, authsize);
  }
  
  static struct aead_request *crypto_rfc4309_crypt(struct aead_request *req)
  {

  	struct crypto_rfc4309_req_ctx *rctx = aead_request_ctx(req);
  	struct aead_request *subreq = &rctx->subreq;

  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(aead);
  	struct crypto_aead *child = ctx->child;

  	struct scatterlist *sg;

  	u8 *iv = PTR_ALIGN((u8 *)(subreq + 1) + crypto_aead_reqsize(child),
  			   crypto_aead_alignmask(child) + 1);
  
  	/* L' */
  	iv[0] = 3;
  
  	memcpy(iv + 1, ctx->nonce, 3);
  	memcpy(iv + 4, req->iv, 8);

  	scatterwalk_map_and_copy(iv + 16, req->src, 0, req->assoclen - 8, 0);
  
  	sg_init_table(rctx->src, 3);
  	sg_set_buf(rctx->src, iv + 16, req->assoclen - 8);
  	sg = scatterwalk_ffwd(rctx->src + 1, req->src, req->assoclen);
  	if (sg != rctx->src + 1)
  		sg_chain(rctx->src, 2, sg);
  
  	if (req->src != req->dst) {
  		sg_init_table(rctx->dst, 3);
  		sg_set_buf(rctx->dst, iv + 16, req->assoclen - 8);
  		sg = scatterwalk_ffwd(rctx->dst + 1, req->dst, req->assoclen);
  		if (sg != rctx->dst + 1)
  			sg_chain(rctx->dst, 2, sg);
  	}

  	aead_request_set_tfm(subreq, child);
  	aead_request_set_callback(subreq, req->base.flags, req->base.complete,
  				  req->base.data);

  	aead_request_set_crypt(subreq, rctx->src,
  			       req->src == req->dst ? rctx->src : rctx->dst,
  			       req->cryptlen, iv);
  	aead_request_set_ad(subreq, req->assoclen - 8);

  
  	return subreq;
  }
  
  static int crypto_rfc4309_encrypt(struct aead_request *req)
  {

  	if (req->assoclen != 16 && req->assoclen != 20)
  		return -EINVAL;

  	req = crypto_rfc4309_crypt(req);
  
  	return crypto_aead_encrypt(req);
  }
  
  static int crypto_rfc4309_decrypt(struct aead_request *req)
  {

  	if (req->assoclen != 16 && req->assoclen != 20)
  		return -EINVAL;

  	req = crypto_rfc4309_crypt(req);
  
  	return crypto_aead_decrypt(req);
  }

  static int crypto_rfc4309_init_tfm(struct crypto_aead *tfm)

  {

  	struct aead_instance *inst = aead_alg_instance(tfm);
  	struct crypto_aead_spawn *spawn = aead_instance_ctx(inst);
  	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(tfm);

  	struct crypto_aead *aead;
  	unsigned long align;
  
  	aead = crypto_spawn_aead(spawn);
  	if (IS_ERR(aead))
  		return PTR_ERR(aead);
  
  	ctx->child = aead;
  
  	align = crypto_aead_alignmask(aead);
  	align &= ~(crypto_tfm_ctx_alignment() - 1);

  	crypto_aead_set_reqsize(
  		tfm,
  		sizeof(struct crypto_rfc4309_req_ctx) +

  		ALIGN(crypto_aead_reqsize(aead), crypto_tfm_ctx_alignment()) +

  		align + 32);

  
  	return 0;
  }

  static void crypto_rfc4309_exit_tfm(struct crypto_aead *tfm)

  {

  	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(tfm);

  
  	crypto_free_aead(ctx->child);
  }

  static void crypto_rfc4309_free(struct aead_instance *inst)
  {
  	crypto_drop_aead(aead_instance_ctx(inst));
  	kfree(inst);
  }
  
  static int crypto_rfc4309_create(struct crypto_template *tmpl,
  				 struct rtattr **tb)

  {
  	struct crypto_attr_type *algt;

  	struct aead_instance *inst;

  	struct crypto_aead_spawn *spawn;

  	struct aead_alg *alg;

  	const char *ccm_name;
  	int err;
  
  	algt = crypto_get_attr_type(tb);

  	if (IS_ERR(algt))

  		return PTR_ERR(algt);

  	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)

  		return -EINVAL;

  
  	ccm_name = crypto_attr_alg_name(tb[1]);

  	if (IS_ERR(ccm_name))

  		return PTR_ERR(ccm_name);

  
  	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
  	if (!inst)

  		return -ENOMEM;

  	spawn = aead_instance_ctx(inst);
  	crypto_set_aead_spawn(spawn, aead_crypto_instance(inst));

  	err = crypto_grab_aead(spawn, ccm_name, 0,
  			       crypto_requires_sync(algt->type, algt->mask));
  	if (err)
  		goto out_free_inst;

  	alg = crypto_spawn_aead_alg(spawn);

  
  	err = -EINVAL;
  
  	/* We only support 16-byte blocks. */

  	if (crypto_aead_alg_ivsize(alg) != 16)

  		goto out_drop_alg;
  
  	/* Not a stream cipher? */

  	if (alg->base.cra_blocksize != 1)

  		goto out_drop_alg;
  
  	err = -ENAMETOOLONG;

  	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
  		     "rfc4309(%s)", alg->base.cra_name) >=
  	    CRYPTO_MAX_ALG_NAME ||
  	    snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
  		     "rfc4309(%s)", alg->base.cra_driver_name) >=

  	    CRYPTO_MAX_ALG_NAME)
  		goto out_drop_alg;

  	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;

  	inst->alg.base.cra_priority = alg->base.cra_priority;
  	inst->alg.base.cra_blocksize = 1;
  	inst->alg.base.cra_alignmask = alg->base.cra_alignmask;

  	inst->alg.ivsize = 8;

  	inst->alg.chunksize = crypto_aead_alg_chunksize(alg);

  	inst->alg.maxauthsize = 16;

  	inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc4309_ctx);

  	inst->alg.init = crypto_rfc4309_init_tfm;
  	inst->alg.exit = crypto_rfc4309_exit_tfm;

  	inst->alg.setkey = crypto_rfc4309_setkey;
  	inst->alg.setauthsize = crypto_rfc4309_setauthsize;
  	inst->alg.encrypt = crypto_rfc4309_encrypt;
  	inst->alg.decrypt = crypto_rfc4309_decrypt;

  	inst->free = crypto_rfc4309_free;
  
  	err = aead_register_instance(tmpl, inst);
  	if (err)
  		goto out_drop_alg;

  
  out:

  	return err;

  
  out_drop_alg:
  	crypto_drop_aead(spawn);
  out_free_inst:
  	kfree(inst);

  	goto out;
  }

  static struct crypto_template crypto_rfc4309_tmpl = {
  	.name = "rfc4309",

  	.create = crypto_rfc4309_create,

  	.module = THIS_MODULE,
  };
  
  static int __init crypto_ccm_module_init(void)
  {
  	int err;
  
  	err = crypto_register_template(&crypto_ccm_base_tmpl);
  	if (err)
  		goto out;
  
  	err = crypto_register_template(&crypto_ccm_tmpl);
  	if (err)
  		goto out_undo_base;
  
  	err = crypto_register_template(&crypto_rfc4309_tmpl);
  	if (err)
  		goto out_undo_ccm;
  
  out:
  	return err;
  
  out_undo_ccm:
  	crypto_unregister_template(&crypto_ccm_tmpl);
  out_undo_base:
  	crypto_unregister_template(&crypto_ccm_base_tmpl);
  	goto out;
  }
  
  static void __exit crypto_ccm_module_exit(void)
  {
  	crypto_unregister_template(&crypto_rfc4309_tmpl);
  	crypto_unregister_template(&crypto_ccm_tmpl);
  	crypto_unregister_template(&crypto_ccm_base_tmpl);
  }
  
  module_init(crypto_ccm_module_init);
  module_exit(crypto_ccm_module_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Counter with CBC MAC");

  MODULE_ALIAS_CRYPTO("ccm_base");
  MODULE_ALIAS_CRYPTO("rfc4309");

  MODULE_ALIAS_CRYPTO("ccm");