/*
   * Cryptographic API.
   *
   * RNG operations.
   *
   * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.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 <linux/atomic.h>

  #include <crypto/internal/rng.h>
  #include <linux/err.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/random.h>
  #include <linux/seq_file.h>

  #include <linux/slab.h>

  #include <linux/string.h>

  #include <linux/cryptouser.h>
  #include <net/netlink.h>

  
  static DEFINE_MUTEX(crypto_default_rng_lock);
  struct crypto_rng *crypto_default_rng;
  EXPORT_SYMBOL_GPL(crypto_default_rng);
  static int crypto_default_rng_refcnt;
  
  static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
  {
  	u8 *buf = NULL;
  	int err;
  
  	if (!seed && slen) {
  		buf = kmalloc(slen, GFP_KERNEL);
  		if (!buf)
  			return -ENOMEM;
  
  		get_random_bytes(buf, slen);
  		seed = buf;
  	}
  
  	err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen);
  
  	kfree(buf);
  	return err;
  }
  
  static int crypto_init_rng_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
  {
  	struct rng_alg *alg = &tfm->__crt_alg->cra_rng;
  	struct rng_tfm *ops = &tfm->crt_rng;
  
  	ops->rng_gen_random = alg->rng_make_random;
  	ops->rng_reset = rngapi_reset;
  
  	return 0;
  }

  #ifdef CONFIG_NET

  static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  {
  	struct crypto_report_rng rrng;
  
  	snprintf(rrng.type, CRYPTO_MAX_ALG_NAME, "%s", "rng");
  
  	rrng.seedsize = alg->cra_rng.seedsize;
  
  	NLA_PUT(skb, CRYPTOCFGA_REPORT_RNG,
  		sizeof(struct crypto_report_rng), &rrng);
  
  	return 0;
  
  nla_put_failure:
  	return -EMSGSIZE;
  }

  #else
  static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  {
  	return -ENOSYS;
  }
  #endif

  static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  	__attribute__ ((unused));
  static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  {
  	seq_printf(m, "type         : rng
  ");
  	seq_printf(m, "seedsize     : %u
  ", alg->cra_rng.seedsize);
  }
  
  static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type,
  				       u32 mask)
  {
  	return alg->cra_ctxsize;
  }
  
  const struct crypto_type crypto_rng_type = {
  	.ctxsize = crypto_rng_ctxsize,
  	.init = crypto_init_rng_ops,
  #ifdef CONFIG_PROC_FS
  	.show = crypto_rng_show,
  #endif

  	.report = crypto_rng_report,

  };
  EXPORT_SYMBOL_GPL(crypto_rng_type);
  
  int crypto_get_default_rng(void)
  {
  	struct crypto_rng *rng;
  	int err;
  
  	mutex_lock(&crypto_default_rng_lock);
  	if (!crypto_default_rng) {
  		rng = crypto_alloc_rng("stdrng", 0, 0);
  		err = PTR_ERR(rng);
  		if (IS_ERR(rng))
  			goto unlock;
  
  		err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
  		if (err) {
  			crypto_free_rng(rng);
  			goto unlock;
  		}
  
  		crypto_default_rng = rng;
  	}
  
  	crypto_default_rng_refcnt++;
  	err = 0;
  
  unlock:
  	mutex_unlock(&crypto_default_rng_lock);
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(crypto_get_default_rng);
  
  void crypto_put_default_rng(void)
  {
  	mutex_lock(&crypto_default_rng_lock);
  	if (!--crypto_default_rng_refcnt) {
  		crypto_free_rng(crypto_default_rng);
  		crypto_default_rng = NULL;
  	}
  	mutex_unlock(&crypto_default_rng_lock);
  }
  EXPORT_SYMBOL_GPL(crypto_put_default_rng);
  
  MODULE_LICENSE("GPL");

  MODULE_DESCRIPTION("Random Number Generator");