crypto/rng.c

   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
  27 static DEFINE_MUTEX(crypto_default_rng_lock);
  28 struct crypto_rng *crypto_default_rng;
  29 EXPORT_SYMBOL_GPL(crypto_default_rng);
  30 static int crypto_default_rng_refcnt;
  31
  32 static 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
  52 static 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
  64 static 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
  77 nla_put_failure:
  78         return -EMSGSIZE;
  79 }
  80 #else
  81 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  82 {
  83         return -ENOSYS;
  84 }
  85 #endif
  86
  87 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  88         __attribute__ ((unused));
  89 static 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
  95 static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type,
  96                                        u32 mask)
  97 {
  98         return alg->cra_ctxsize;
  99 }
 100
 101 const 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 };
 109 EXPORT_SYMBOL_GPL(crypto_rng_type);
 110
 111 int 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
 135 unlock:
 136         mutex_unlock(&crypto_default_rng_lock);
 137
 138         return err;
 139 }
 140 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 141
 142 void 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 }
 151 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 152
 153 MODULE_LICENSE("GPL");
 154 MODULE_DESCRIPTION("Random Number Generator");