text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * CCM: Counter with CBC-MAC
   *
   * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
   */
  
  #include <crypto/internal/aead.h>
  #include <crypto/internal/hash.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>
  
  struct ccm_instance_ctx {
  	struct crypto_skcipher_spawn ctr;
  	struct crypto_ahash_spawn mac;
  };
  
  struct crypto_ccm_ctx {
  	struct crypto_ahash *mac;
  	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 flags;
  	struct scatterlist src[3];
  	struct scatterlist dst[3];
  	union {
  		struct ahash_request ahreq;
  		struct skcipher_request skreq;
  	};
  };
  
  struct cbcmac_tfm_ctx {
  	struct crypto_cipher *child;
  };
  
  struct cbcmac_desc_ctx {
  	unsigned int len;
  };
  
  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_ahash *mac = ctx->mac;
  	int err;
  
  	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);
  	if (err)
  		return err;
  
  	crypto_ahash_clear_flags(mac, CRYPTO_TFM_REQ_MASK);
  	crypto_ahash_set_flags(mac, crypto_aead_get_flags(aead) &
  				    CRYPTO_TFM_REQ_MASK);
  	return crypto_ahash_setkey(mac, key, keylen);
  }
  
  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 int crypto_ccm_auth(struct aead_request *req, struct scatterlist *plain,
  			   unsigned int cryptlen)
  {
  	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
  	struct ahash_request *ahreq = &pctx->ahreq;
  	unsigned int assoclen = req->assoclen;
  	struct scatterlist sg[3];
  	u8 *odata = pctx->odata;
  	u8 *idata = pctx->idata;
  	int ilen, err;
  
  	/* format control data for input */
  	err = format_input(odata, req, cryptlen);
  	if (err)
  		goto out;
  
  	sg_init_table(sg, 3);
  	sg_set_buf(&sg[0], odata, 16);
  
  	/* format associated data and compute into mac */
  	if (assoclen) {
  		ilen = format_adata(idata, assoclen);
  		sg_set_buf(&sg[1], idata, ilen);
  		sg_chain(sg, 3, req->src);
  	} else {
  		ilen = 0;
  		sg_chain(sg, 2, req->src);
  	}
  
  	ahash_request_set_tfm(ahreq, ctx->mac);
  	ahash_request_set_callback(ahreq, pctx->flags, NULL, NULL);
  	ahash_request_set_crypt(ahreq, sg, NULL, assoclen + ilen + 16);
  	err = crypto_ahash_init(ahreq);
  	if (err)
  		goto out;
  	err = crypto_ahash_update(ahreq);
  	if (err)
  		goto out;
  
  	/* we need to pad the MAC input to a round multiple of the block size */
  	ilen = 16 - (assoclen + ilen) % 16;
  	if (ilen < 16) {
  		memset(idata, 0, ilen);
  		sg_init_table(sg, 2);
  		sg_set_buf(&sg[0], idata, ilen);
  		if (plain)
  			sg_chain(sg, 2, plain);
  		plain = sg;
  		cryptlen += ilen;
  	}
  
  	ahash_request_set_crypt(ahreq, plain, pctx->odata, cryptlen);
  	err = crypto_ahash_finup(ahreq);
  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 = pctx->idata;
  	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;
  
  	memcpy(iv, req->iv, 16);
  
  	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_ahash *mac;
  	struct crypto_skcipher *ctr;
  	unsigned long align;
  	int err;
  
  	mac = crypto_spawn_ahash(&ictx->mac);
  	if (IS_ERR(mac))
  		return PTR_ERR(mac);
  
  	ctr = crypto_spawn_skcipher(&ictx->ctr);
  	err = PTR_ERR(ctr);
  	if (IS_ERR(ctr))
  		goto err_free_mac;
  
  	ctx->mac = mac;
  	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) +
  		max(crypto_ahash_reqsize(mac), crypto_skcipher_reqsize(ctr)));
  
  	return 0;
  
  err_free_mac:
  	crypto_free_ahash(mac);
  	return err;
  }
  
  static void crypto_ccm_exit_tfm(struct crypto_aead *tfm)
  {
  	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(tfm);
  
  	crypto_free_ahash(ctx->mac);
  	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_ahash(&ctx->mac);
  	crypto_drop_skcipher(&ctx->ctr);
  	kfree(inst);
  }
  
  static int crypto_ccm_create_common(struct crypto_template *tmpl,
  				    struct rtattr **tb,
  				    const char *ctr_name,
  				    const char *mac_name)
  {
  	struct crypto_attr_type *algt;
  	u32 mask;
  	struct aead_instance *inst;
  	struct ccm_instance_ctx *ictx;
  	struct skcipher_alg *ctr;
  	struct hash_alg_common *mac;
  	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;
  
  	mask = crypto_requires_sync(algt->type, algt->mask);
  
  	inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
  	if (!inst)
  		return -ENOMEM;
  	ictx = aead_instance_ctx(inst);
  
  	err = crypto_grab_ahash(&ictx->mac, aead_crypto_instance(inst),
  				mac_name, 0, CRYPTO_ALG_ASYNC);
  	if (err)
  		goto err_free_inst;
  	mac = crypto_spawn_ahash_alg(&ictx->mac);
  
  	err = -EINVAL;
  	if (strncmp(mac->base.cra_name, "cbcmac(", 7) != 0 ||
  	    mac->digestsize != 16)
  		goto err_free_inst;
  
  	err = crypto_grab_skcipher(&ictx->ctr, aead_crypto_instance(inst),
  				   ctr_name, 0, mask);
  	if (err)
  		goto err_free_inst;
  	ctr = crypto_spawn_skcipher_alg(&ictx->ctr);
  
  	/* The skcipher algorithm must be CTR mode, using 16-byte blocks. */
  	err = -EINVAL;
  	if (strncmp(ctr->base.cra_name, "ctr(", 4) != 0 ||
  	    crypto_skcipher_alg_ivsize(ctr) != 16 ||
  	    ctr->base.cra_blocksize != 1)
  		goto err_free_inst;
  
  	/* ctr and cbcmac must use the same underlying block cipher. */
  	if (strcmp(ctr->base.cra_name + 4, mac->base.cra_name + 7) != 0)
  		goto err_free_inst;
  
  	err = -ENAMETOOLONG;
  	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
  		     "ccm(%s", ctr->base.cra_name + 4) >= CRYPTO_MAX_ALG_NAME)
  		goto err_free_inst;
  
  	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
  		     "ccm_base(%s,%s)", ctr->base.cra_driver_name,
  		     mac->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
  		goto err_free_inst;
  
  	inst->alg.base.cra_flags = ctr->base.cra_flags & CRYPTO_ALG_ASYNC;
  	inst->alg.base.cra_priority = (mac->base.cra_priority +
  				       ctr->base.cra_priority) / 2;
  	inst->alg.base.cra_blocksize = 1;
  	inst->alg.base.cra_alignmask = mac->base.cra_alignmask |
  				       ctr->base.cra_alignmask;
  	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) {
  err_free_inst:
  		crypto_ccm_free(inst);
  	}
  	return err;
  }
  
  static int crypto_ccm_create(struct crypto_template *tmpl, struct rtattr **tb)
  {
  	const char *cipher_name;
  	char ctr_name[CRYPTO_MAX_ALG_NAME];
  	char mac_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(mac_name, CRYPTO_MAX_ALG_NAME, "cbcmac(%s)",
  		     cipher_name) >= CRYPTO_MAX_ALG_NAME)
  		return -ENAMETOOLONG;
  
  	return crypto_ccm_create_common(tmpl, tb, ctr_name, mac_name);
  }
  
  static int crypto_ccm_base_create(struct crypto_template *tmpl,
  				  struct rtattr **tb)
  {
  	const char *ctr_name;
  	const char *mac_name;
  
  	ctr_name = crypto_attr_alg_name(tb[1]);
  	if (IS_ERR(ctr_name))
  		return PTR_ERR(ctr_name);
  
  	mac_name = crypto_attr_alg_name(tb[2]);
  	if (IS_ERR(mac_name))
  		return PTR_ERR(mac_name);
  
  	return crypto_ccm_create_common(tmpl, tb, ctr_name, mac_name);
  }
  
  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;
  
  	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);
  	return crypto_aead_setkey(child, key, keylen);
  }
  
  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;
  	u32 mask;
  	struct aead_instance *inst;
  	struct crypto_aead_spawn *spawn;
  	struct aead_alg *alg;
  	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;
  
  	mask = crypto_requires_sync(algt->type, algt->mask);
  
  	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
  	if (!inst)
  		return -ENOMEM;
  
  	spawn = aead_instance_ctx(inst);
  	err = crypto_grab_aead(spawn, aead_crypto_instance(inst),
  			       crypto_attr_alg_name(tb[1]), 0, mask);
  	if (err)
  		goto err_free_inst;
  
  	alg = crypto_spawn_aead_alg(spawn);
  
  	err = -EINVAL;
  
  	/* We only support 16-byte blocks. */
  	if (crypto_aead_alg_ivsize(alg) != 16)
  		goto err_free_inst;
  
  	/* Not a stream cipher? */
  	if (alg->base.cra_blocksize != 1)
  		goto err_free_inst;
  
  	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 err_free_inst;
  
  	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) {
  err_free_inst:
  		crypto_rfc4309_free(inst);
  	}
  	return err;
  }
  
  static int crypto_cbcmac_digest_setkey(struct crypto_shash *parent,
  				     const u8 *inkey, unsigned int keylen)
  {
  	struct cbcmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
  
  	return crypto_cipher_setkey(ctx->child, inkey, keylen);
  }
  
  static int crypto_cbcmac_digest_init(struct shash_desc *pdesc)
  {
  	struct cbcmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
  	int bs = crypto_shash_digestsize(pdesc->tfm);
  	u8 *dg = (u8 *)ctx + crypto_shash_descsize(pdesc->tfm) - bs;
  
  	ctx->len = 0;
  	memset(dg, 0, bs);
  
  	return 0;
  }
  
  static int crypto_cbcmac_digest_update(struct shash_desc *pdesc, const u8 *p,
  				       unsigned int len)
  {
  	struct crypto_shash *parent = pdesc->tfm;
  	struct cbcmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
  	struct cbcmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
  	struct crypto_cipher *tfm = tctx->child;
  	int bs = crypto_shash_digestsize(parent);
  	u8 *dg = (u8 *)ctx + crypto_shash_descsize(parent) - bs;
  
  	while (len > 0) {
  		unsigned int l = min(len, bs - ctx->len);
  
  		crypto_xor(dg + ctx->len, p, l);
  		ctx->len +=l;
  		len -= l;
  		p += l;
  
  		if (ctx->len == bs) {
  			crypto_cipher_encrypt_one(tfm, dg, dg);
  			ctx->len = 0;
  		}
  	}
  
  	return 0;
  }
  
  static int crypto_cbcmac_digest_final(struct shash_desc *pdesc, u8 *out)
  {
  	struct crypto_shash *parent = pdesc->tfm;
  	struct cbcmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
  	struct cbcmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
  	struct crypto_cipher *tfm = tctx->child;
  	int bs = crypto_shash_digestsize(parent);
  	u8 *dg = (u8 *)ctx + crypto_shash_descsize(parent) - bs;
  
  	if (ctx->len)
  		crypto_cipher_encrypt_one(tfm, dg, dg);
  
  	memcpy(out, dg, bs);
  	return 0;
  }
  
  static int cbcmac_init_tfm(struct crypto_tfm *tfm)
  {
  	struct crypto_cipher *cipher;
  	struct crypto_instance *inst = (void *)tfm->__crt_alg;
  	struct crypto_cipher_spawn *spawn = crypto_instance_ctx(inst);
  	struct cbcmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
  
  	cipher = crypto_spawn_cipher(spawn);
  	if (IS_ERR(cipher))
  		return PTR_ERR(cipher);
  
  	ctx->child = cipher;
  
  	return 0;
  };
  
  static void cbcmac_exit_tfm(struct crypto_tfm *tfm)
  {
  	struct cbcmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
  	crypto_free_cipher(ctx->child);
  }
  
  static int cbcmac_create(struct crypto_template *tmpl, struct rtattr **tb)
  {
  	struct shash_instance *inst;
  	struct crypto_cipher_spawn *spawn;
  	struct crypto_alg *alg;
  	int err;
  
  	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
  	if (err)
  		return err;
  
  	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
  	if (!inst)
  		return -ENOMEM;
  	spawn = shash_instance_ctx(inst);
  
  	err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),
  				 crypto_attr_alg_name(tb[1]), 0, 0);
  	if (err)
  		goto err_free_inst;
  	alg = crypto_spawn_cipher_alg(spawn);
  
  	err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
  	if (err)
  		goto err_free_inst;
  
  	inst->alg.base.cra_priority = alg->cra_priority;
  	inst->alg.base.cra_blocksize = 1;
  
  	inst->alg.digestsize = alg->cra_blocksize;
  	inst->alg.descsize = ALIGN(sizeof(struct cbcmac_desc_ctx),
  				   alg->cra_alignmask + 1) +
  			     alg->cra_blocksize;
  
  	inst->alg.base.cra_ctxsize = sizeof(struct cbcmac_tfm_ctx);
  	inst->alg.base.cra_init = cbcmac_init_tfm;
  	inst->alg.base.cra_exit = cbcmac_exit_tfm;
  
  	inst->alg.init = crypto_cbcmac_digest_init;
  	inst->alg.update = crypto_cbcmac_digest_update;
  	inst->alg.final = crypto_cbcmac_digest_final;
  	inst->alg.setkey = crypto_cbcmac_digest_setkey;
  
  	inst->free = shash_free_singlespawn_instance;
  
  	err = shash_register_instance(tmpl, inst);
  	if (err) {
  err_free_inst:
  		shash_free_singlespawn_instance(inst);
  	}
  	return err;
  }
  
  static struct crypto_template crypto_ccm_tmpls[] = {
  	{
  		.name = "cbcmac",
  		.create = cbcmac_create,
  		.module = THIS_MODULE,
  	}, {
  		.name = "ccm_base",
  		.create = crypto_ccm_base_create,
  		.module = THIS_MODULE,
  	}, {
  		.name = "ccm",
  		.create = crypto_ccm_create,
  		.module = THIS_MODULE,
  	}, {
  		.name = "rfc4309",
  		.create = crypto_rfc4309_create,
  		.module = THIS_MODULE,
  	},
  };
  
  static int __init crypto_ccm_module_init(void)
  {
  	return crypto_register_templates(crypto_ccm_tmpls,
  					 ARRAY_SIZE(crypto_ccm_tmpls));
  }
  
  static void __exit crypto_ccm_module_exit(void)
  {
  	crypto_unregister_templates(crypto_ccm_tmpls,
  				    ARRAY_SIZE(crypto_ccm_tmpls));
  }
  
  subsys_initcall(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");
  MODULE_ALIAS_CRYPTO("cbcmac");
  