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 25 static DEFINE_MUTEX(crypto_default_rng_lock); 26 struct crypto_rng *crypto_default_rng; 27 EXPORT_SYMBOL_GPL(crypto_default_rng); 28 static int crypto_default_rng_refcnt; 29 30 static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen) 31 { 32 u8 *buf = NULL; 33 int err; 34 35 if (!seed && slen) { 36 buf = kmalloc(slen, GFP_KERNEL); 37 if (!buf) 38 return -ENOMEM; 39 40 get_random_bytes(buf, slen); 41 seed = buf; 42 } 43 44 err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen); 45 46 kfree(buf); 47 return err; 48 } 49 50 static int crypto_init_rng_ops(struct crypto_tfm *tfm, u32 type, u32 mask) 51 { 52 struct rng_alg *alg = &tfm->__crt_alg->cra_rng; 53 struct rng_tfm *ops = &tfm->crt_rng; 54 55 ops->rng_gen_random = alg->rng_make_random; 56 ops->rng_reset = rngapi_reset; 57 58 return 0; 59 } 60 61 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 62 __attribute__ ((unused)); 63 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 64 { 65 seq_printf(m, "type : rng\n"); 66 seq_printf(m, "seedsize : %u\n", alg->cra_rng.seedsize); 67 } 68 69 static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type, 70 u32 mask) 71 { 72 return alg->cra_ctxsize; 73 } 74 75 const struct crypto_type crypto_rng_type = { 76 .ctxsize = crypto_rng_ctxsize, 77 .init = crypto_init_rng_ops, 78 #ifdef CONFIG_PROC_FS 79 .show = crypto_rng_show, 80 #endif 81 }; 82 EXPORT_SYMBOL_GPL(crypto_rng_type); 83 84 int crypto_get_default_rng(void) 85 { 86 struct crypto_rng *rng; 87 int err; 88 89 mutex_lock(&crypto_default_rng_lock); 90 if (!crypto_default_rng) { 91 rng = crypto_alloc_rng("stdrng", 0, 0); 92 err = PTR_ERR(rng); 93 if (IS_ERR(rng)) 94 goto unlock; 95 96 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 97 if (err) { 98 crypto_free_rng(rng); 99 goto unlock; 100 } 101 102 crypto_default_rng = rng; 103 } 104 105 crypto_default_rng_refcnt++; 106 err = 0; 107 108 unlock: 109 mutex_unlock(&crypto_default_rng_lock); 110 111 return err; 112 } 113 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 114 115 void crypto_put_default_rng(void) 116 { 117 mutex_lock(&crypto_default_rng_lock); 118 if (!--crypto_default_rng_refcnt) { 119 crypto_free_rng(crypto_default_rng); 120 crypto_default_rng = NULL; 121 } 122 mutex_unlock(&crypto_default_rng_lock); 123 } 124 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 125 126 MODULE_LICENSE("GPL"); 127 MODULE_DESCRIPTION("Random Number Generator"); 128