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"); 155