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 #include "internal.h"
  28
  29 static DEFINE_MUTEX(crypto_default_rng_lock);
  30 struct crypto_rng *crypto_default_rng;
  31 EXPORT_SYMBOL_GPL(crypto_default_rng);
  32 static int crypto_default_rng_refcnt;
  33
  34 static inline struct crypto_rng *__crypto_rng_cast(struct crypto_tfm *tfm)
  35 {
  36         return container_of(tfm, struct crypto_rng, base);
  37 }
  38
  39 static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
  40 {
  41         u8 *buf = NULL;
  42         int err;
  43
  44         if (!seed && slen) {
  45                 buf = kmalloc(slen, GFP_KERNEL);
  46                 if (!buf)
  47                         return -ENOMEM;
  48
  49                 get_random_bytes(buf, slen);
  50                 seed = buf;
  51         }
  52
  53         err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen);
  54
  55         kfree(buf);
  56         return err;
  57 }
  58
  59 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
  60 {
  61         struct crypto_rng *rng = __crypto_rng_cast(tfm);
  62         struct rng_alg *alg = &tfm->__crt_alg->cra_rng;
  63
  64         rng->generate = alg->rng_make_random;
  65         rng->seed = rngapi_reset;
  66
  67         return 0;
  68 }
  69
  70 #ifdef CONFIG_NET
  71 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  72 {
  73         struct crypto_report_rng rrng;
  74
  75         strncpy(rrng.type, "rng", sizeof(rrng.type));
  76
  77         rrng.seedsize = alg->cra_rng.seedsize;
  78
  79         if (nla_put(skb, CRYPTOCFGA_REPORT_RNG,
  80                     sizeof(struct crypto_report_rng), &rrng))
  81                 goto nla_put_failure;
  82         return 0;
  83
  84 nla_put_failure:
  85         return -EMSGSIZE;
  86 }
  87 #else
  88 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
  89 {
  90         return -ENOSYS;
  91 }
  92 #endif
  93
  94 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  95         __attribute__ ((unused));
  96 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
  97 {
  98         seq_printf(m, "type         : rng\n");
  99         seq_printf(m, "seedsize     : %u\n", alg->cra_rng.seedsize);
 100 }
 101
 102 const struct crypto_type crypto_rng_type = {
 103         .extsize = crypto_alg_extsize,
 104         .init_tfm = crypto_rng_init_tfm,
 105 #ifdef CONFIG_PROC_FS
 106         .show = crypto_rng_show,
 107 #endif
 108         .report = crypto_rng_report,
 109         .maskclear = ~CRYPTO_ALG_TYPE_MASK,
 110         .maskset = CRYPTO_ALG_TYPE_MASK,
 111         .type = CRYPTO_ALG_TYPE_RNG,
 112         .tfmsize = offsetof(struct crypto_rng, base),
 113 };
 114 EXPORT_SYMBOL_GPL(crypto_rng_type);
 115
 116 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
 117 {
 118         return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
 119 }
 120 EXPORT_SYMBOL_GPL(crypto_alloc_rng);
 121
 122 int crypto_get_default_rng(void)
 123 {
 124         struct crypto_rng *rng;
 125         int err;
 126
 127         mutex_lock(&crypto_default_rng_lock);
 128         if (!crypto_default_rng) {
 129                 rng = crypto_alloc_rng("stdrng", 0, 0);
 130                 err = PTR_ERR(rng);
 131                 if (IS_ERR(rng))
 132                         goto unlock;
 133
 134                 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
 135                 if (err) {
 136                         crypto_free_rng(rng);
 137                         goto unlock;
 138                 }
 139
 140                 crypto_default_rng = rng;
 141         }
 142
 143         crypto_default_rng_refcnt++;
 144         err = 0;
 145
 146 unlock:
 147         mutex_unlock(&crypto_default_rng_lock);
 148
 149         return err;
 150 }
 151 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 152
 153 void crypto_put_default_rng(void)
 154 {
 155         mutex_lock(&crypto_default_rng_lock);
 156         if (!--crypto_default_rng_refcnt) {
 157                 crypto_free_rng(crypto_default_rng);
 158                 crypto_default_rng = NULL;
 159         }
 160         mutex_unlock(&crypto_default_rng_lock);
 161 }
 162 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 163
 164 MODULE_LICENSE("GPL");
 165 MODULE_DESCRIPTION("Random Number Generator");