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 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 64 { 65 struct crypto_report_rng rrng; 66 67 snprintf(rrng.type, CRYPTO_MAX_ALG_NAME, "%s", "rng"); 68 69 rrng.seedsize = alg->cra_rng.seedsize; 70 71 NLA_PUT(skb, CRYPTOCFGA_REPORT_RNG, 72 sizeof(struct crypto_report_rng), &rrng); 73 74 return 0; 75 76 nla_put_failure: 77 return -EMSGSIZE; 78 } 79 80 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 81 __attribute__ ((unused)); 82 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 83 { 84 seq_printf(m, "type : rng\n"); 85 seq_printf(m, "seedsize : %u\n", alg->cra_rng.seedsize); 86 } 87 88 static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type, 89 u32 mask) 90 { 91 return alg->cra_ctxsize; 92 } 93 94 const struct crypto_type crypto_rng_type = { 95 .ctxsize = crypto_rng_ctxsize, 96 .init = crypto_init_rng_ops, 97 #ifdef CONFIG_PROC_FS 98 .show = crypto_rng_show, 99 #endif 100 .report = crypto_rng_report, 101 }; 102 EXPORT_SYMBOL_GPL(crypto_rng_type); 103 104 int crypto_get_default_rng(void) 105 { 106 struct crypto_rng *rng; 107 int err; 108 109 mutex_lock(&crypto_default_rng_lock); 110 if (!crypto_default_rng) { 111 rng = crypto_alloc_rng("stdrng", 0, 0); 112 err = PTR_ERR(rng); 113 if (IS_ERR(rng)) 114 goto unlock; 115 116 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 117 if (err) { 118 crypto_free_rng(rng); 119 goto unlock; 120 } 121 122 crypto_default_rng = rng; 123 } 124 125 crypto_default_rng_refcnt++; 126 err = 0; 127 128 unlock: 129 mutex_unlock(&crypto_default_rng_lock); 130 131 return err; 132 } 133 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 134 135 void crypto_put_default_rng(void) 136 { 137 mutex_lock(&crypto_default_rng_lock); 138 if (!--crypto_default_rng_refcnt) { 139 crypto_free_rng(crypto_default_rng); 140 crypto_default_rng = NULL; 141 } 142 mutex_unlock(&crypto_default_rng_lock); 143 } 144 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 145 146 MODULE_LICENSE("GPL"); 147 MODULE_DESCRIPTION("Random Number Generator"); 148