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 <asm/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/string.h> 23 24 static DEFINE_MUTEX(crypto_default_rng_lock); 25 struct crypto_rng *crypto_default_rng; 26 EXPORT_SYMBOL_GPL(crypto_default_rng); 27 static int crypto_default_rng_refcnt; 28 29 static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen) 30 { 31 u8 *buf = NULL; 32 int err; 33 34 if (!seed && slen) { 35 buf = kmalloc(slen, GFP_KERNEL); 36 if (!buf) 37 return -ENOMEM; 38 39 get_random_bytes(buf, slen); 40 seed = buf; 41 } 42 43 err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen); 44 45 kfree(buf); 46 return err; 47 } 48 49 static int crypto_init_rng_ops(struct crypto_tfm *tfm, u32 type, u32 mask) 50 { 51 struct rng_alg *alg = &tfm->__crt_alg->cra_rng; 52 struct rng_tfm *ops = &tfm->crt_rng; 53 54 ops->rng_gen_random = alg->rng_make_random; 55 ops->rng_reset = rngapi_reset; 56 57 return 0; 58 } 59 60 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 61 __attribute__ ((unused)); 62 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 63 { 64 seq_printf(m, "type : rng\n"); 65 seq_printf(m, "seedsize : %u\n", alg->cra_rng.seedsize); 66 } 67 68 static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type, 69 u32 mask) 70 { 71 return alg->cra_ctxsize; 72 } 73 74 const struct crypto_type crypto_rng_type = { 75 .ctxsize = crypto_rng_ctxsize, 76 .init = crypto_init_rng_ops, 77 #ifdef CONFIG_PROC_FS 78 .show = crypto_rng_show, 79 #endif 80 }; 81 EXPORT_SYMBOL_GPL(crypto_rng_type); 82 83 int crypto_get_default_rng(void) 84 { 85 struct crypto_rng *rng; 86 int err; 87 88 mutex_lock(&crypto_default_rng_lock); 89 if (!crypto_default_rng) { 90 rng = crypto_alloc_rng("stdrng", 0, 0); 91 err = PTR_ERR(rng); 92 if (IS_ERR(rng)) 93 goto unlock; 94 95 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 96 if (err) { 97 crypto_free_rng(rng); 98 goto unlock; 99 } 100 101 crypto_default_rng = rng; 102 } 103 104 crypto_default_rng_refcnt++; 105 err = 0; 106 107 unlock: 108 mutex_unlock(&crypto_default_rng_lock); 109 110 return err; 111 } 112 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 113 114 void crypto_put_default_rng(void) 115 { 116 mutex_lock(&crypto_default_rng_lock); 117 if (!--crypto_default_rng_refcnt) { 118 crypto_free_rng(crypto_default_rng); 119 crypto_default_rng = NULL; 120 } 121 mutex_unlock(&crypto_default_rng_lock); 122 } 123 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 124 125 MODULE_LICENSE("GPL"); 126 MODULE_DESCRIPTION("Random Number Genertor"); 127