/*
   * GCM: Galois/Counter Mode.
   *
   * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published
   * by the Free Software Foundation.
   */

  #include <crypto/gf128mul.h>

  #include <crypto/internal/aead.h>

  #include <crypto/internal/skcipher.h>

  #include <crypto/scatterwalk.h>

  #include <linux/completion.h>

  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/slab.h>

  struct gcm_instance_ctx {

  	struct crypto_skcipher_spawn ctr;

  };
  
  struct crypto_gcm_ctx {
  	struct crypto_ablkcipher *ctr;
  	struct gf128mul_4k *gf128;
  };

  struct crypto_rfc4106_ctx {
  	struct crypto_aead *child;
  	u8 nonce[4];
  };

  struct crypto_gcm_ghash_ctx {
  	u32 bytes;
  	u32 flags;
  	struct gf128mul_4k *gf128;
  	u8 buffer[16];
  };
  
  struct crypto_gcm_req_priv_ctx {
  	u8 auth_tag[16];

  	u8 iauth_tag[16];

  	struct scatterlist src[2];
  	struct scatterlist dst[2];

  	struct crypto_gcm_ghash_ctx ghash;

  	struct ablkcipher_request abreq;

  };

  struct crypto_gcm_setkey_result {
  	int err;
  	struct completion completion;
  };

  static inline struct crypto_gcm_req_priv_ctx *crypto_gcm_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 void crypto_gcm_ghash_init(struct crypto_gcm_ghash_ctx *ctx, u32 flags,
  				  struct gf128mul_4k *gf128)
  {
  	ctx->bytes = 0;
  	ctx->flags = flags;
  	ctx->gf128 = gf128;
  	memset(ctx->buffer, 0, 16);
  }
  
  static void crypto_gcm_ghash_update(struct crypto_gcm_ghash_ctx *ctx,
  				    const u8 *src, unsigned int srclen)
  {
  	u8 *dst = ctx->buffer;
  
  	if (ctx->bytes) {
  		int n = min(srclen, ctx->bytes);
  		u8 *pos = dst + (16 - ctx->bytes);
  
  		ctx->bytes -= n;
  		srclen -= n;
  
  		while (n--)
  			*pos++ ^= *src++;
  
  		if (!ctx->bytes)
  			gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  	}
  
  	while (srclen >= 16) {
  		crypto_xor(dst, src, 16);
  		gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  		src += 16;
  		srclen -= 16;
  	}
  
  	if (srclen) {
  		ctx->bytes = 16 - srclen;
  		while (srclen--)
  			*dst++ ^= *src++;
  	}
  }
  
  static void crypto_gcm_ghash_update_sg(struct crypto_gcm_ghash_ctx *ctx,
  				       struct scatterlist *sg, int len)
  {
  	struct scatter_walk walk;
  	u8 *src;
  	int n;

  	if (!len)
  		return;

  	scatterwalk_start(&walk, sg);
  
  	while (len) {
  		n = scatterwalk_clamp(&walk, len);
  
  		if (!n) {

  			scatterwalk_start(&walk, scatterwalk_sg_next(walk.sg));

  			n = scatterwalk_clamp(&walk, len);
  		}
  
  		src = scatterwalk_map(&walk, 0);
  
  		crypto_gcm_ghash_update(ctx, src, n);
  		len -= n;
  
  		scatterwalk_unmap(src, 0);
  		scatterwalk_advance(&walk, n);
  		scatterwalk_done(&walk, 0, len);
  		if (len)
  			crypto_yield(ctx->flags);
  	}
  }
  
  static void crypto_gcm_ghash_flush(struct crypto_gcm_ghash_ctx *ctx)
  {
  	u8 *dst = ctx->buffer;
  
  	if (ctx->bytes) {
  		u8 *tmp = dst + (16 - ctx->bytes);
  
  		while (ctx->bytes--)
  			*tmp++ ^= 0;
  
  		gf128mul_4k_lle((be128 *)dst, ctx->gf128);
  	}
  
  	ctx->bytes = 0;
  }
  
  static void crypto_gcm_ghash_final_xor(struct crypto_gcm_ghash_ctx *ctx,
  				       unsigned int authlen,
  				       unsigned int cryptlen, u8 *dst)
  {
  	u8 *buf = ctx->buffer;
  	u128 lengths;
  
  	lengths.a = cpu_to_be64(authlen * 8);
  	lengths.b = cpu_to_be64(cryptlen * 8);
  
  	crypto_gcm_ghash_flush(ctx);
  	crypto_xor(buf, (u8 *)&lengths, 16);
  	gf128mul_4k_lle((be128 *)buf, ctx->gf128);
  	crypto_xor(dst, buf, 16);
  }

  static void crypto_gcm_setkey_done(struct crypto_async_request *req, int err)

  {

  	struct crypto_gcm_setkey_result *result = req->data;

  	if (err == -EINPROGRESS)
  		return;
  
  	result->err = err;
  	complete(&result->completion);

  }
  
  static int crypto_gcm_setkey(struct crypto_aead *aead, const u8 *key,
  			     unsigned int keylen)
  {
  	struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
  	struct crypto_ablkcipher *ctr = ctx->ctr;

  	struct {
  		be128 hash;
  		u8 iv[8];
  
  		struct crypto_gcm_setkey_result result;
  
  		struct scatterlist sg[1];
  		struct ablkcipher_request req;
  	} *data;
  	int err;

  
  	crypto_ablkcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK);
  	crypto_ablkcipher_set_flags(ctr, crypto_aead_get_flags(aead) &
  				   CRYPTO_TFM_REQ_MASK);
  
  	err = crypto_ablkcipher_setkey(ctr, key, keylen);
  	if (err)

  		return err;

  
  	crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctr) &
  				       CRYPTO_TFM_RES_MASK);

  	data = kzalloc(sizeof(*data) + crypto_ablkcipher_reqsize(ctr),
  		       GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	init_completion(&data->result.completion);
  	sg_init_one(data->sg, &data->hash, sizeof(data->hash));
  	ablkcipher_request_set_tfm(&data->req, ctr);
  	ablkcipher_request_set_callback(&data->req, CRYPTO_TFM_REQ_MAY_SLEEP |
  						    CRYPTO_TFM_REQ_MAY_BACKLOG,
  					crypto_gcm_setkey_done,
  					&data->result);
  	ablkcipher_request_set_crypt(&data->req, data->sg, data->sg,
  				     sizeof(data->hash), data->iv);
  
  	err = crypto_ablkcipher_encrypt(&data->req);
  	if (err == -EINPROGRESS || err == -EBUSY) {
  		err = wait_for_completion_interruptible(
  			&data->result.completion);
  		if (!err)
  			err = data->result.err;
  	}

  	if (err)
  		goto out;
  
  	if (ctx->gf128 != NULL)
  		gf128mul_free_4k(ctx->gf128);

  	ctx->gf128 = gf128mul_init_4k_lle(&data->hash);

  
  	if (ctx->gf128 == NULL)
  		err = -ENOMEM;

  out:
  	kfree(data);

  	return err;
  }

  static int crypto_gcm_setauthsize(struct crypto_aead *tfm,
  				  unsigned int authsize)
  {
  	switch (authsize) {
  	case 4:
  	case 8:
  	case 12:
  	case 13:
  	case 14:
  	case 15:
  	case 16:
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	return 0;
  }

  static void crypto_gcm_init_crypt(struct ablkcipher_request *ablk_req,
  				  struct aead_request *req,
  				  unsigned int cryptlen)

  {
  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);

  	struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);

  	u32 flags = req->base.tfm->crt_flags;

  	struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;

  	struct scatterlist *dst;
  	__be32 counter = cpu_to_be32(1);
  
  	memset(pctx->auth_tag, 0, sizeof(pctx->auth_tag));
  	memcpy(req->iv + 12, &counter, 4);
  
  	sg_init_table(pctx->src, 2);
  	sg_set_buf(pctx->src, pctx->auth_tag, sizeof(pctx->auth_tag));
  	scatterwalk_sg_chain(pctx->src, 2, req->src);
  
  	dst = pctx->src;
  	if (req->src != req->dst) {
  		sg_init_table(pctx->dst, 2);
  		sg_set_buf(pctx->dst, pctx->auth_tag, sizeof(pctx->auth_tag));
  		scatterwalk_sg_chain(pctx->dst, 2, req->dst);
  		dst = pctx->dst;
  	}

  
  	ablkcipher_request_set_tfm(ablk_req, ctx->ctr);

  	ablkcipher_request_set_crypt(ablk_req, pctx->src, dst,
  				     cryptlen + sizeof(pctx->auth_tag),
  				     req->iv);

  
  	crypto_gcm_ghash_init(ghash, flags, ctx->gf128);

  	crypto_gcm_ghash_update_sg(ghash, req->assoc, req->assoclen);
  	crypto_gcm_ghash_flush(ghash);

  }

  static int crypto_gcm_hash(struct aead_request *req)

  {

  	struct crypto_aead *aead = crypto_aead_reqtfm(req);

  	struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);

  	u8 *auth_tag = pctx->auth_tag;
  	struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
  
  	crypto_gcm_ghash_update_sg(ghash, req->dst, req->cryptlen);
  	crypto_gcm_ghash_final_xor(ghash, req->assoclen, req->cryptlen,
  				   auth_tag);

  	scatterwalk_map_and_copy(auth_tag, req->dst, req->cryptlen,
  				 crypto_aead_authsize(aead), 1);
  	return 0;
  }
  
  static void crypto_gcm_encrypt_done(struct crypto_async_request *areq, int err)
  {
  	struct aead_request *req = areq->data;
  
  	if (!err)
  		err = crypto_gcm_hash(req);

  	aead_request_complete(req, err);
  }
  
  static int crypto_gcm_encrypt(struct aead_request *req)
  {

  	struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);

  	struct ablkcipher_request *abreq = &pctx->abreq;

  	int err;
  
  	crypto_gcm_init_crypt(abreq, req, req->cryptlen);
  	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
  					crypto_gcm_encrypt_done, req);

  	err = crypto_ablkcipher_encrypt(abreq);

  	if (err)
  		return err;

  	return crypto_gcm_hash(req);

  }

  static int crypto_gcm_verify(struct aead_request *req)
  {
  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
  	struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
  	u8 *auth_tag = pctx->auth_tag;
  	u8 *iauth_tag = pctx->iauth_tag;
  	unsigned int authsize = crypto_aead_authsize(aead);
  	unsigned int cryptlen = req->cryptlen - authsize;
  
  	crypto_gcm_ghash_final_xor(ghash, req->assoclen, cryptlen, auth_tag);
  
  	authsize = crypto_aead_authsize(aead);
  	scatterwalk_map_and_copy(iauth_tag, req->src, cryptlen, authsize, 0);
  	return memcmp(iauth_tag, auth_tag, authsize) ? -EBADMSG : 0;
  }

  static void crypto_gcm_decrypt_done(struct crypto_async_request *areq, int err)
  {

  	struct aead_request *req = areq->data;
  
  	if (!err)
  		err = crypto_gcm_verify(req);
  
  	aead_request_complete(req, err);

  }
  
  static int crypto_gcm_decrypt(struct aead_request *req)
  {

  	struct crypto_aead *aead = crypto_aead_reqtfm(req);

  	struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);

  	struct ablkcipher_request *abreq = &pctx->abreq;

  	struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;

  	unsigned int cryptlen = req->cryptlen;
  	unsigned int authsize = crypto_aead_authsize(aead);

  	int err;

  	if (cryptlen < authsize)

  		return -EINVAL;

  	cryptlen -= authsize;

  	crypto_gcm_init_crypt(abreq, req, cryptlen);
  	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
  					crypto_gcm_decrypt_done, req);

  	crypto_gcm_ghash_update_sg(ghash, req->src, cryptlen);

  	err = crypto_ablkcipher_decrypt(abreq);
  	if (err)
  		return err;

  	return crypto_gcm_verify(req);

  }
  
  static int crypto_gcm_init_tfm(struct crypto_tfm *tfm)
  {
  	struct crypto_instance *inst = (void *)tfm->__crt_alg;
  	struct gcm_instance_ctx *ictx = crypto_instance_ctx(inst);
  	struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(tfm);
  	struct crypto_ablkcipher *ctr;
  	unsigned long align;
  	int err;

  	ctr = crypto_spawn_skcipher(&ictx->ctr);

  	err = PTR_ERR(ctr);
  	if (IS_ERR(ctr))
  		return err;
  
  	ctx->ctr = ctr;
  	ctx->gf128 = NULL;

  	align = crypto_tfm_alg_alignmask(tfm);

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

  	tfm->crt_aead.reqsize = align +
  				sizeof(struct crypto_gcm_req_priv_ctx) +
  				crypto_ablkcipher_reqsize(ctr);

  
  	return 0;
  }
  
  static void crypto_gcm_exit_tfm(struct crypto_tfm *tfm)
  {
  	struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(tfm);
  
  	if (ctx->gf128 != NULL)
  		gf128mul_free_4k(ctx->gf128);
  
  	crypto_free_ablkcipher(ctx->ctr);
  }

  static struct crypto_instance *crypto_gcm_alloc_common(struct rtattr **tb,
  						       const char *full_name,
  						       const char *ctr_name)

  {

  	struct crypto_attr_type *algt;

  	struct crypto_instance *inst;
  	struct crypto_alg *ctr;

  	struct gcm_instance_ctx *ctx;
  	int err;

  	algt = crypto_get_attr_type(tb);
  	err = PTR_ERR(algt);
  	if (IS_ERR(algt))

  		return ERR_PTR(err);

  	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
  		return ERR_PTR(-EINVAL);

  	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
  	if (!inst)
  		return ERR_PTR(-ENOMEM);

  	ctx = crypto_instance_ctx(inst);
  	crypto_set_skcipher_spawn(&ctx->ctr, inst);
  	err = crypto_grab_skcipher(&ctx->ctr, ctr_name, 0,
  				   crypto_requires_sync(algt->type,
  							algt->mask));
  	if (err)
  		goto err_free_inst;
  
  	ctr = crypto_skcipher_spawn_alg(&ctx->ctr);

  	/* We only support 16-byte blocks. */

  	if (ctr->cra_ablkcipher.ivsize != 16)

  		goto out_put_ctr;
  
  	/* Not a stream cipher? */
  	err = -EINVAL;
  	if (ctr->cra_blocksize != 1)

  		goto out_put_ctr;

  	err = -ENAMETOOLONG;

  	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
  		     "gcm_base(%s)", ctr->cra_driver_name) >=
  	    CRYPTO_MAX_ALG_NAME)

  		goto out_put_ctr;

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

  	inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
  	inst->alg.cra_flags |= ctr->cra_flags & CRYPTO_ALG_ASYNC;

  	inst->alg.cra_priority = ctr->cra_priority;

  	inst->alg.cra_blocksize = 1;

  	inst->alg.cra_alignmask = ctr->cra_alignmask | (__alignof__(u64) - 1);

  	inst->alg.cra_type = &crypto_aead_type;

  	inst->alg.cra_aead.ivsize = 16;

  	inst->alg.cra_aead.maxauthsize = 16;

  	inst->alg.cra_ctxsize = sizeof(struct crypto_gcm_ctx);
  	inst->alg.cra_init = crypto_gcm_init_tfm;
  	inst->alg.cra_exit = crypto_gcm_exit_tfm;
  	inst->alg.cra_aead.setkey = crypto_gcm_setkey;

  	inst->alg.cra_aead.setauthsize = crypto_gcm_setauthsize;

  	inst->alg.cra_aead.encrypt = crypto_gcm_encrypt;
  	inst->alg.cra_aead.decrypt = crypto_gcm_decrypt;
  
  out:

  	return inst;

  
  out_put_ctr:
  	crypto_drop_skcipher(&ctx->ctr);

  err_free_inst:
  	kfree(inst);

  	inst = ERR_PTR(err);
  	goto out;
  }

  static struct crypto_instance *crypto_gcm_alloc(struct rtattr **tb)
  {
  	int err;
  	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]);
  	err = PTR_ERR(cipher_name);
  	if (IS_ERR(cipher_name))
  		return ERR_PTR(err);
  
  	if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)", cipher_name) >=
  	    CRYPTO_MAX_ALG_NAME)
  		return ERR_PTR(-ENAMETOOLONG);
  
  	if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "gcm(%s)", cipher_name) >=
  	    CRYPTO_MAX_ALG_NAME)
  		return ERR_PTR(-ENAMETOOLONG);
  
  	return crypto_gcm_alloc_common(tb, full_name, ctr_name);
  }

  static void crypto_gcm_free(struct crypto_instance *inst)
  {
  	struct gcm_instance_ctx *ctx = crypto_instance_ctx(inst);

  	crypto_drop_skcipher(&ctx->ctr);

  	kfree(inst);
  }
  
  static struct crypto_template crypto_gcm_tmpl = {
  	.name = "gcm",
  	.alloc = crypto_gcm_alloc,
  	.free = crypto_gcm_free,
  	.module = THIS_MODULE,
  };

  static struct crypto_instance *crypto_gcm_base_alloc(struct rtattr **tb)
  {
  	int err;
  	const char *ctr_name;
  	char full_name[CRYPTO_MAX_ALG_NAME];
  
  	ctr_name = crypto_attr_alg_name(tb[1]);
  	err = PTR_ERR(ctr_name);
  	if (IS_ERR(ctr_name))
  		return ERR_PTR(err);
  
  	if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "gcm_base(%s)",
  		     ctr_name) >= CRYPTO_MAX_ALG_NAME)
  		return ERR_PTR(-ENAMETOOLONG);
  
  	return crypto_gcm_alloc_common(tb, full_name, ctr_name);
  }
  
  static struct crypto_template crypto_gcm_base_tmpl = {
  	.name = "gcm_base",
  	.alloc = crypto_gcm_base_alloc,
  	.free = crypto_gcm_free,
  	.module = THIS_MODULE,
  };

  static int crypto_rfc4106_setkey(struct crypto_aead *parent, const u8 *key,
  				 unsigned int keylen)
  {
  	struct crypto_rfc4106_ctx *ctx = crypto_aead_ctx(parent);
  	struct crypto_aead *child = ctx->child;
  	int err;
  
  	if (keylen < 4)
  		return -EINVAL;
  
  	keylen -= 4;
  	memcpy(ctx->nonce, key + keylen, 4);
  
  	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_rfc4106_setauthsize(struct crypto_aead *parent,
  				      unsigned int authsize)
  {
  	struct crypto_rfc4106_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_rfc4106_crypt(struct aead_request *req)
  {
  	struct aead_request *subreq = aead_request_ctx(req);
  	struct crypto_aead *aead = crypto_aead_reqtfm(req);
  	struct crypto_rfc4106_ctx *ctx = crypto_aead_ctx(aead);
  	struct crypto_aead *child = ctx->child;
  	u8 *iv = PTR_ALIGN((u8 *)(subreq + 1) + crypto_aead_reqsize(child),
  			   crypto_aead_alignmask(child) + 1);
  
  	memcpy(iv, ctx->nonce, 4);
  	memcpy(iv + 4, req->iv, 8);
  
  	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, req->src, req->dst, req->cryptlen, iv);
  	aead_request_set_assoc(subreq, req->assoc, req->assoclen);
  
  	return subreq;
  }
  
  static int crypto_rfc4106_encrypt(struct aead_request *req)
  {
  	req = crypto_rfc4106_crypt(req);
  
  	return crypto_aead_encrypt(req);
  }
  
  static int crypto_rfc4106_decrypt(struct aead_request *req)
  {
  	req = crypto_rfc4106_crypt(req);
  
  	return crypto_aead_decrypt(req);
  }
  
  static int crypto_rfc4106_init_tfm(struct crypto_tfm *tfm)
  {
  	struct crypto_instance *inst = (void *)tfm->__crt_alg;
  	struct crypto_aead_spawn *spawn = crypto_instance_ctx(inst);
  	struct crypto_rfc4106_ctx *ctx = crypto_tfm_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);
  	tfm->crt_aead.reqsize = sizeof(struct aead_request) +
  				ALIGN(crypto_aead_reqsize(aead),
  				      crypto_tfm_ctx_alignment()) +
  				align + 16;
  
  	return 0;
  }
  
  static void crypto_rfc4106_exit_tfm(struct crypto_tfm *tfm)
  {
  	struct crypto_rfc4106_ctx *ctx = crypto_tfm_ctx(tfm);
  
  	crypto_free_aead(ctx->child);
  }
  
  static struct crypto_instance *crypto_rfc4106_alloc(struct rtattr **tb)
  {
  	struct crypto_attr_type *algt;
  	struct crypto_instance *inst;
  	struct crypto_aead_spawn *spawn;
  	struct crypto_alg *alg;
  	const char *ccm_name;
  	int err;
  
  	algt = crypto_get_attr_type(tb);
  	err = PTR_ERR(algt);
  	if (IS_ERR(algt))
  		return ERR_PTR(err);
  
  	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
  		return ERR_PTR(-EINVAL);
  
  	ccm_name = crypto_attr_alg_name(tb[1]);
  	err = PTR_ERR(ccm_name);
  	if (IS_ERR(ccm_name))
  		return ERR_PTR(err);
  
  	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
  	if (!inst)
  		return ERR_PTR(-ENOMEM);
  
  	spawn = crypto_instance_ctx(inst);
  	crypto_set_aead_spawn(spawn, inst);
  	err = crypto_grab_aead(spawn, ccm_name, 0,
  			       crypto_requires_sync(algt->type, algt->mask));
  	if (err)
  		goto out_free_inst;
  
  	alg = crypto_aead_spawn_alg(spawn);
  
  	err = -EINVAL;
  
  	/* We only support 16-byte blocks. */
  	if (alg->cra_aead.ivsize != 16)
  		goto out_drop_alg;
  
  	/* Not a stream cipher? */
  	if (alg->cra_blocksize != 1)
  		goto out_drop_alg;
  
  	err = -ENAMETOOLONG;
  	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
  		     "rfc4106(%s)", alg->cra_name) >= CRYPTO_MAX_ALG_NAME ||
  	    snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
  		     "rfc4106(%s)", alg->cra_driver_name) >=
  	    CRYPTO_MAX_ALG_NAME)
  		goto out_drop_alg;
  
  	inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
  	inst->alg.cra_flags |= alg->cra_flags & CRYPTO_ALG_ASYNC;
  	inst->alg.cra_priority = alg->cra_priority;
  	inst->alg.cra_blocksize = 1;
  	inst->alg.cra_alignmask = alg->cra_alignmask;
  	inst->alg.cra_type = &crypto_nivaead_type;
  
  	inst->alg.cra_aead.ivsize = 8;
  	inst->alg.cra_aead.maxauthsize = 16;
  
  	inst->alg.cra_ctxsize = sizeof(struct crypto_rfc4106_ctx);
  
  	inst->alg.cra_init = crypto_rfc4106_init_tfm;
  	inst->alg.cra_exit = crypto_rfc4106_exit_tfm;
  
  	inst->alg.cra_aead.setkey = crypto_rfc4106_setkey;
  	inst->alg.cra_aead.setauthsize = crypto_rfc4106_setauthsize;
  	inst->alg.cra_aead.encrypt = crypto_rfc4106_encrypt;
  	inst->alg.cra_aead.decrypt = crypto_rfc4106_decrypt;
  
  	inst->alg.cra_aead.geniv = "seqiv";
  
  out:
  	return inst;
  
  out_drop_alg:
  	crypto_drop_aead(spawn);
  out_free_inst:
  	kfree(inst);
  	inst = ERR_PTR(err);
  	goto out;
  }
  
  static void crypto_rfc4106_free(struct crypto_instance *inst)
  {
  	crypto_drop_spawn(crypto_instance_ctx(inst));
  	kfree(inst);
  }
  
  static struct crypto_template crypto_rfc4106_tmpl = {
  	.name = "rfc4106",
  	.alloc = crypto_rfc4106_alloc,
  	.free = crypto_rfc4106_free,
  	.module = THIS_MODULE,
  };

  static int __init crypto_gcm_module_init(void)
  {

  	int err;
  
  	err = crypto_register_template(&crypto_gcm_base_tmpl);
  	if (err)
  		goto out;
  
  	err = crypto_register_template(&crypto_gcm_tmpl);
  	if (err)
  		goto out_undo_base;

  	err = crypto_register_template(&crypto_rfc4106_tmpl);
  	if (err)
  		goto out_undo_gcm;

  out:
  	return err;

  out_undo_gcm:
  	crypto_unregister_template(&crypto_gcm_tmpl);

  out_undo_base:
  	crypto_unregister_template(&crypto_gcm_base_tmpl);
  	goto out;

  }
  
  static void __exit crypto_gcm_module_exit(void)
  {

  	crypto_unregister_template(&crypto_rfc4106_tmpl);

  	crypto_unregister_template(&crypto_gcm_tmpl);

  	crypto_unregister_template(&crypto_gcm_base_tmpl);

  }
  
  module_init(crypto_gcm_module_init);
  module_exit(crypto_gcm_module_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Galois/Counter Mode");
  MODULE_AUTHOR("Mikko Herranen <mh1@iki.fi>");

  MODULE_ALIAS("gcm_base");

  MODULE_ALIAS("rfc4106");