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 out: 54 kzfree(buf); 55 return err; 56 } 57 EXPORT_SYMBOL_GPL(crypto_rng_reset); 58 59 static int crypto_rng_init_tfm(struct crypto_tfm *tfm) 60 { 61 return 0; 62 } 63 64 static unsigned int seedsize(struct crypto_alg *alg) 65 { 66 struct rng_alg *ralg = container_of(alg, struct rng_alg, base); 67 68 return ralg->seedsize; 69 } 70 71 #ifdef CONFIG_NET 72 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 73 { 74 struct crypto_report_rng rrng; 75 76 strncpy(rrng.type, "rng", sizeof(rrng.type)); 77 78 rrng.seedsize = seedsize(alg); 79 80 if (nla_put(skb, CRYPTOCFGA_REPORT_RNG, 81 sizeof(struct crypto_report_rng), &rrng)) 82 goto nla_put_failure; 83 return 0; 84 85 nla_put_failure: 86 return -EMSGSIZE; 87 } 88 #else 89 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 90 { 91 return -ENOSYS; 92 } 93 #endif 94 95 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 96 __maybe_unused; 97 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 98 { 99 seq_printf(m, "type : rng\n"); 100 seq_printf(m, "seedsize : %u\n", seedsize(alg)); 101 } 102 103 static const struct crypto_type crypto_rng_type = { 104 .extsize = crypto_alg_extsize, 105 .init_tfm = crypto_rng_init_tfm, 106 #ifdef CONFIG_PROC_FS 107 .show = crypto_rng_show, 108 #endif 109 .report = crypto_rng_report, 110 .maskclear = ~CRYPTO_ALG_TYPE_MASK, 111 .maskset = CRYPTO_ALG_TYPE_MASK, 112 .type = CRYPTO_ALG_TYPE_RNG, 113 .tfmsize = offsetof(struct crypto_rng, base), 114 }; 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 crypto_default_rng_refcnt--; 157 mutex_unlock(&crypto_default_rng_lock); 158 } 159 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 160 161 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE) 162 int crypto_del_default_rng(void) 163 { 164 int err = -EBUSY; 165 166 mutex_lock(&crypto_default_rng_lock); 167 if (crypto_default_rng_refcnt) 168 goto out; 169 170 crypto_free_rng(crypto_default_rng); 171 crypto_default_rng = NULL; 172 173 err = 0; 174 175 out: 176 mutex_unlock(&crypto_default_rng_lock); 177 178 return err; 179 } 180 EXPORT_SYMBOL_GPL(crypto_del_default_rng); 181 #endif 182 183 int crypto_register_rng(struct rng_alg *alg) 184 { 185 struct crypto_alg *base = &alg->base; 186 187 if (alg->seedsize > PAGE_SIZE / 8) 188 return -EINVAL; 189 190 base->cra_type = &crypto_rng_type; 191 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK; 192 base->cra_flags |= CRYPTO_ALG_TYPE_RNG; 193 194 return crypto_register_alg(base); 195 } 196 EXPORT_SYMBOL_GPL(crypto_register_rng); 197 198 void crypto_unregister_rng(struct rng_alg *alg) 199 { 200 crypto_unregister_alg(&alg->base); 201 } 202 EXPORT_SYMBOL_GPL(crypto_unregister_rng); 203 204 int crypto_register_rngs(struct rng_alg *algs, int count) 205 { 206 int i, ret; 207 208 for (i = 0; i < count; i++) { 209 ret = crypto_register_rng(algs + i); 210 if (ret) 211 goto err; 212 } 213 214 return 0; 215 216 err: 217 for (--i; i >= 0; --i) 218 crypto_unregister_rng(algs + i); 219 220 return ret; 221 } 222 EXPORT_SYMBOL_GPL(crypto_register_rngs); 223 224 void crypto_unregister_rngs(struct rng_alg *algs, int count) 225 { 226 int i; 227 228 for (i = count - 1; i >= 0; --i) 229 crypto_unregister_rng(algs + i); 230 } 231 EXPORT_SYMBOL_GPL(crypto_unregister_rngs); 232 233 MODULE_LICENSE("GPL"); 234 MODULE_DESCRIPTION("Random Number Generator"); 235