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"); 166