1 /* 2 * Cryptographic API. 3 * 4 * RNG operations. 5 * 6 * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com> 7 * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au> 8 * 9 * This program is free software; you can redistribute it and/or modify it 10 * under the terms of the GNU General Public License as published by the Free 11 * Software Foundation; either version 2 of the License, or (at your option) 12 * any later version. 13 * 14 */ 15 16 #include <linux/atomic.h> 17 #include <crypto/internal/rng.h> 18 #include <linux/err.h> 19 #include <linux/module.h> 20 #include <linux/mutex.h> 21 #include <linux/random.h> 22 #include <linux/seq_file.h> 23 #include <linux/slab.h> 24 #include <linux/string.h> 25 #include <linux/cryptouser.h> 26 #include <linux/compiler.h> 27 #include <net/netlink.h> 28 29 #include "internal.h" 30 31 static DEFINE_MUTEX(crypto_default_rng_lock); 32 struct crypto_rng *crypto_default_rng; 33 EXPORT_SYMBOL_GPL(crypto_default_rng); 34 static int crypto_default_rng_refcnt; 35 36 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen) 37 { 38 u8 *buf = NULL; 39 int err; 40 41 if (!seed && slen) { 42 buf = kmalloc(slen, GFP_KERNEL); 43 if (!buf) 44 return -ENOMEM; 45 46 err = get_random_bytes_wait(buf, slen); 47 if (err) 48 goto out; 49 seed = buf; 50 } 51 52 err = crypto_rng_alg(tfm)->seed(tfm, seed, slen); 53 crypto_stat_rng_seed(tfm, err); 54 out: 55 kzfree(buf); 56 return err; 57 } 58 EXPORT_SYMBOL_GPL(crypto_rng_reset); 59 60 static int crypto_rng_init_tfm(struct crypto_tfm *tfm) 61 { 62 return 0; 63 } 64 65 static unsigned int seedsize(struct crypto_alg *alg) 66 { 67 struct rng_alg *ralg = container_of(alg, struct rng_alg, base); 68 69 return ralg->seedsize; 70 } 71 72 #ifdef CONFIG_NET 73 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 74 { 75 struct crypto_report_rng rrng; 76 77 strncpy(rrng.type, "rng", sizeof(rrng.type)); 78 79 rrng.seedsize = seedsize(alg); 80 81 if (nla_put(skb, CRYPTOCFGA_REPORT_RNG, 82 sizeof(struct crypto_report_rng), &rrng)) 83 goto nla_put_failure; 84 return 0; 85 86 nla_put_failure: 87 return -EMSGSIZE; 88 } 89 #else 90 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 91 { 92 return -ENOSYS; 93 } 94 #endif 95 96 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 97 __maybe_unused; 98 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 99 { 100 seq_printf(m, "type : rng\n"); 101 seq_printf(m, "seedsize : %u\n", seedsize(alg)); 102 } 103 104 static const struct crypto_type crypto_rng_type = { 105 .extsize = crypto_alg_extsize, 106 .init_tfm = crypto_rng_init_tfm, 107 #ifdef CONFIG_PROC_FS 108 .show = crypto_rng_show, 109 #endif 110 .report = crypto_rng_report, 111 .maskclear = ~CRYPTO_ALG_TYPE_MASK, 112 .maskset = CRYPTO_ALG_TYPE_MASK, 113 .type = CRYPTO_ALG_TYPE_RNG, 114 .tfmsize = offsetof(struct crypto_rng, base), 115 }; 116 117 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask) 118 { 119 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask); 120 } 121 EXPORT_SYMBOL_GPL(crypto_alloc_rng); 122 123 int crypto_get_default_rng(void) 124 { 125 struct crypto_rng *rng; 126 int err; 127 128 mutex_lock(&crypto_default_rng_lock); 129 if (!crypto_default_rng) { 130 rng = crypto_alloc_rng("stdrng", 0, 0); 131 err = PTR_ERR(rng); 132 if (IS_ERR(rng)) 133 goto unlock; 134 135 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 136 if (err) { 137 crypto_free_rng(rng); 138 goto unlock; 139 } 140 141 crypto_default_rng = rng; 142 } 143 144 crypto_default_rng_refcnt++; 145 err = 0; 146 147 unlock: 148 mutex_unlock(&crypto_default_rng_lock); 149 150 return err; 151 } 152 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 153 154 void crypto_put_default_rng(void) 155 { 156 mutex_lock(&crypto_default_rng_lock); 157 crypto_default_rng_refcnt--; 158 mutex_unlock(&crypto_default_rng_lock); 159 } 160 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 161 162 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE) 163 int crypto_del_default_rng(void) 164 { 165 int err = -EBUSY; 166 167 mutex_lock(&crypto_default_rng_lock); 168 if (crypto_default_rng_refcnt) 169 goto out; 170 171 crypto_free_rng(crypto_default_rng); 172 crypto_default_rng = NULL; 173 174 err = 0; 175 176 out: 177 mutex_unlock(&crypto_default_rng_lock); 178 179 return err; 180 } 181 EXPORT_SYMBOL_GPL(crypto_del_default_rng); 182 #endif 183 184 int crypto_register_rng(struct rng_alg *alg) 185 { 186 struct crypto_alg *base = &alg->base; 187 188 if (alg->seedsize > PAGE_SIZE / 8) 189 return -EINVAL; 190 191 base->cra_type = &crypto_rng_type; 192 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK; 193 base->cra_flags |= CRYPTO_ALG_TYPE_RNG; 194 195 return crypto_register_alg(base); 196 } 197 EXPORT_SYMBOL_GPL(crypto_register_rng); 198 199 void crypto_unregister_rng(struct rng_alg *alg) 200 { 201 crypto_unregister_alg(&alg->base); 202 } 203 EXPORT_SYMBOL_GPL(crypto_unregister_rng); 204 205 int crypto_register_rngs(struct rng_alg *algs, int count) 206 { 207 int i, ret; 208 209 for (i = 0; i < count; i++) { 210 ret = crypto_register_rng(algs + i); 211 if (ret) 212 goto err; 213 } 214 215 return 0; 216 217 err: 218 for (--i; i >= 0; --i) 219 crypto_unregister_rng(algs + i); 220 221 return ret; 222 } 223 EXPORT_SYMBOL_GPL(crypto_register_rngs); 224 225 void crypto_unregister_rngs(struct rng_alg *algs, int count) 226 { 227 int i; 228 229 for (i = count - 1; i >= 0; --i) 230 crypto_unregister_rng(algs + i); 231 } 232 EXPORT_SYMBOL_GPL(crypto_unregister_rngs); 233 234 MODULE_LICENSE("GPL"); 235 MODULE_DESCRIPTION("Random Number Generator"); 236