linux/crypto/rng.c
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   1/*
   2 * Cryptographic API.
   3 *
   4 * RNG operations.
   5 *
   6 * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
   7 *
   8 * This program is free software; you can redistribute it and/or modify it
   9 * under the terms of the GNU General Public License as published by the Free
  10 * Software Foundation; either version 2 of the License, or (at your option)
  11 * any later version.
  12 *
  13 */
  14
  15#include <linux/atomic.h>
  16#include <crypto/internal/rng.h>
  17#include <linux/err.h>
  18#include <linux/module.h>
  19#include <linux/mutex.h>
  20#include <linux/random.h>
  21#include <linux/seq_file.h>
  22#include <linux/slab.h>
  23#include <linux/string.h>
  24#include <linux/cryptouser.h>
  25#include <net/netlink.h>
  26
  27static DEFINE_MUTEX(crypto_default_rng_lock);
  28struct crypto_rng *crypto_default_rng;
  29EXPORT_SYMBOL_GPL(crypto_default_rng);
  30static int crypto_default_rng_refcnt;
  31
  32static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
  33{
  34        u8 *buf = NULL;
  35        int err;
  36
  37        if (!seed && slen) {
  38                buf = kmalloc(slen, GFP_KERNEL);
  39                if (!buf)
  40                        return -ENOMEM;
  41
  42                get_random_bytes(buf, slen);
  43                seed = buf;
  44        }
  45
  46        err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen);
  47
  48        kfree(buf);
  49        return err;
  50}
  51
  52static int crypto_init_rng_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
  53{
  54        struct rng_alg *alg = &tfm->__crt_alg->cra_rng;
  55        struct rng_tfm *ops = &tfm->crt_rng;
  56
  57        ops->rng_gen_random = alg->rng_make_random;
  58        ops->rng_reset = rngapi_reset;
  59
  60        return 0;
  61}
  62
  63#ifdef CONFIG_NET
  64static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  65{
  66        struct crypto_report_rng rrng;
  67
  68        strncpy(rrng.type, "rng", sizeof(rrng.type));
  69
  70        rrng.seedsize = alg->cra_rng.seedsize;
  71
  72        if (nla_put(skb, CRYPTOCFGA_REPORT_RNG,
  73                    sizeof(struct crypto_report_rng), &rrng))
  74                goto nla_put_failure;
  75        return 0;
  76
  77nla_put_failure:
  78        return -EMSGSIZE;
  79}
  80#else
  81static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  82{
  83        return -ENOSYS;
  84}
  85#endif
  86
  87static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  88        __attribute__ ((unused));
  89static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  90{
  91        seq_printf(m, "type         : rng\n");
  92        seq_printf(m, "seedsize     : %u\n", alg->cra_rng.seedsize);
  93}
  94
  95static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type,
  96                                       u32 mask)
  97{
  98        return alg->cra_ctxsize;
  99}
 100
 101const struct crypto_type crypto_rng_type = {
 102        .ctxsize = crypto_rng_ctxsize,
 103        .init = crypto_init_rng_ops,
 104#ifdef CONFIG_PROC_FS
 105        .show = crypto_rng_show,
 106#endif
 107        .report = crypto_rng_report,
 108};
 109EXPORT_SYMBOL_GPL(crypto_rng_type);
 110
 111int crypto_get_default_rng(void)
 112{
 113        struct crypto_rng *rng;
 114        int err;
 115
 116        mutex_lock(&crypto_default_rng_lock);
 117        if (!crypto_default_rng) {
 118                rng = crypto_alloc_rng("stdrng", 0, 0);
 119                err = PTR_ERR(rng);
 120                if (IS_ERR(rng))
 121                        goto unlock;
 122
 123                err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
 124                if (err) {
 125                        crypto_free_rng(rng);
 126                        goto unlock;
 127                }
 128
 129                crypto_default_rng = rng;
 130        }
 131
 132        crypto_default_rng_refcnt++;
 133        err = 0;
 134
 135unlock:
 136        mutex_unlock(&crypto_default_rng_lock);
 137
 138        return err;
 139}
 140EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 141
 142void crypto_put_default_rng(void)
 143{
 144        mutex_lock(&crypto_default_rng_lock);
 145        if (!--crypto_default_rng_refcnt) {
 146                crypto_free_rng(crypto_default_rng);
 147                crypto_default_rng = NULL;
 148        }
 149        mutex_unlock(&crypto_default_rng_lock);
 150}
 151EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 152
 153MODULE_LICENSE("GPL");
 154MODULE_DESCRIPTION("Random Number Generator");
 155
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