// SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * geniv: Shared IV generator code
   *
   * This file provides common code to IV generators such as seqiv.
   *
   * Copyright (c) 2007-2019 Herbert Xu <herbert@gondor.apana.org.au>
   */
  
  #include <crypto/internal/geniv.h>
  #include <crypto/internal/rng.h>
  #include <crypto/null.h>
  #include <linux/err.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/rtnetlink.h>
  #include <linux/slab.h>
  
  static int aead_geniv_setkey(struct crypto_aead *tfm,
  			     const u8 *key, unsigned int keylen)
  {
  	struct aead_geniv_ctx *ctx = crypto_aead_ctx(tfm);
  
  	return crypto_aead_setkey(ctx->child, key, keylen);
  }
  
  static int aead_geniv_setauthsize(struct crypto_aead *tfm,
  				  unsigned int authsize)
  {
  	struct aead_geniv_ctx *ctx = crypto_aead_ctx(tfm);
  
  	return crypto_aead_setauthsize(ctx->child, authsize);
  }

  static void aead_geniv_free(struct aead_instance *inst)
  {
  	crypto_drop_aead(aead_instance_ctx(inst));
  	kfree(inst);
  }

  struct aead_instance *aead_geniv_alloc(struct crypto_template *tmpl,

  				       struct rtattr **tb)

  {

  	struct crypto_aead_spawn *spawn;

  	struct aead_instance *inst;
  	struct aead_alg *alg;
  	unsigned int ivsize;
  	unsigned int maxauthsize;

  	u32 mask;

  	int err;

  	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
  	if (err)
  		return ERR_PTR(err);

  	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
  	if (!inst)
  		return ERR_PTR(-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);
  
  	ivsize = crypto_aead_alg_ivsize(alg);
  	maxauthsize = crypto_aead_alg_maxauthsize(alg);
  
  	err = -EINVAL;
  	if (ivsize < sizeof(u64))

  		goto err_free_inst;

  
  	err = -ENAMETOOLONG;
  	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
  		     "%s(%s)", tmpl->name, alg->base.cra_name) >=
  	    CRYPTO_MAX_ALG_NAME)

  		goto err_free_inst;

  	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
  		     "%s(%s)", tmpl->name, alg->base.cra_driver_name) >=
  	    CRYPTO_MAX_ALG_NAME)

  		goto err_free_inst;

  	inst->alg.base.cra_priority = alg->base.cra_priority;
  	inst->alg.base.cra_blocksize = alg->base.cra_blocksize;
  	inst->alg.base.cra_alignmask = alg->base.cra_alignmask;
  	inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
  
  	inst->alg.setkey = aead_geniv_setkey;
  	inst->alg.setauthsize = aead_geniv_setauthsize;
  
  	inst->alg.ivsize = ivsize;
  	inst->alg.maxauthsize = maxauthsize;

  	inst->free = aead_geniv_free;

  out:
  	return inst;

  err_free_inst:

  	aead_geniv_free(inst);

  	inst = ERR_PTR(err);
  	goto out;
  }
  EXPORT_SYMBOL_GPL(aead_geniv_alloc);

  int aead_init_geniv(struct crypto_aead *aead)
  {
  	struct aead_geniv_ctx *ctx = crypto_aead_ctx(aead);
  	struct aead_instance *inst = aead_alg_instance(aead);
  	struct crypto_aead *child;
  	int err;
  
  	spin_lock_init(&ctx->lock);
  
  	err = crypto_get_default_rng();
  	if (err)
  		goto out;
  
  	err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
  				   crypto_aead_ivsize(aead));
  	crypto_put_default_rng();
  	if (err)
  		goto out;
  
  	ctx->sknull = crypto_get_default_null_skcipher();
  	err = PTR_ERR(ctx->sknull);
  	if (IS_ERR(ctx->sknull))
  		goto out;
  
  	child = crypto_spawn_aead(aead_instance_ctx(inst));
  	err = PTR_ERR(child);
  	if (IS_ERR(child))
  		goto drop_null;
  
  	ctx->child = child;
  	crypto_aead_set_reqsize(aead, crypto_aead_reqsize(child) +
  				      sizeof(struct aead_request));
  
  	err = 0;
  
  out:
  	return err;
  
  drop_null:
  	crypto_put_default_null_skcipher();
  	goto out;
  }
  EXPORT_SYMBOL_GPL(aead_init_geniv);
  
  void aead_exit_geniv(struct crypto_aead *tfm)
  {
  	struct aead_geniv_ctx *ctx = crypto_aead_ctx(tfm);
  
  	crypto_free_aead(ctx->child);
  	crypto_put_default_null_skcipher();
  }
  EXPORT_SYMBOL_GPL(aead_exit_geniv);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Shared IV generator code");