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 static inline struct crypto_rng *__crypto_rng_cast(struct crypto_tfm *tfm) 37 { 38 return container_of(tfm, struct crypto_rng, base); 39 } 40 41 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen) 42 { 43 u8 *buf = NULL; 44 int err; 45 46 if (!seed && slen) { 47 buf = kmalloc(slen, GFP_KERNEL); 48 if (!buf) 49 return -ENOMEM; 50 51 get_random_bytes(buf, slen); 52 seed = buf; 53 } 54 55 err = crypto_rng_alg(tfm)->seed(tfm, seed, slen); 56 57 kzfree(buf); 58 return err; 59 } 60 EXPORT_SYMBOL_GPL(crypto_rng_reset); 61 62 static int crypto_rng_init_tfm(struct crypto_tfm *tfm) 63 { 64 return 0; 65 } 66 67 static unsigned int seedsize(struct crypto_alg *alg) 68 { 69 struct rng_alg *ralg = container_of(alg, struct rng_alg, base); 70 71 return ralg->seedsize; 72 } 73 74 #ifdef CONFIG_NET 75 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 76 { 77 struct crypto_report_rng rrng; 78 79 strncpy(rrng.type, "rng", sizeof(rrng.type)); 80 81 rrng.seedsize = seedsize(alg); 82 83 if (nla_put(skb, CRYPTOCFGA_REPORT_RNG, 84 sizeof(struct crypto_report_rng), &rrng)) 85 goto nla_put_failure; 86 return 0; 87 88 nla_put_failure: 89 return -EMSGSIZE; 90 } 91 #else 92 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 93 { 94 return -ENOSYS; 95 } 96 #endif 97 98 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 99 __maybe_unused; 100 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 101 { 102 seq_printf(m, "type : rng\n"); 103 seq_printf(m, "seedsize : %u\n", seedsize(alg)); 104 } 105 106 static const struct crypto_type crypto_rng_type = { 107 .extsize = crypto_alg_extsize, 108 .init_tfm = crypto_rng_init_tfm, 109 #ifdef CONFIG_PROC_FS 110 .show = crypto_rng_show, 111 #endif 112 .report = crypto_rng_report, 113 .maskclear = ~CRYPTO_ALG_TYPE_MASK, 114 .maskset = CRYPTO_ALG_TYPE_MASK, 115 .type = CRYPTO_ALG_TYPE_RNG, 116 .tfmsize = offsetof(struct crypto_rng, base), 117 }; 118 119 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask) 120 { 121 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask); 122 } 123 EXPORT_SYMBOL_GPL(crypto_alloc_rng); 124 125 int crypto_get_default_rng(void) 126 { 127 struct crypto_rng *rng; 128 int err; 129 130 mutex_lock(&crypto_default_rng_lock); 131 if (!crypto_default_rng) { 132 rng = crypto_alloc_rng("stdrng", 0, 0); 133 err = PTR_ERR(rng); 134 if (IS_ERR(rng)) 135 goto unlock; 136 137 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 138 if (err) { 139 crypto_free_rng(rng); 140 goto unlock; 141 } 142 143 crypto_default_rng = rng; 144 } 145 146 crypto_default_rng_refcnt++; 147 err = 0; 148 149 unlock: 150 mutex_unlock(&crypto_default_rng_lock); 151 152 return err; 153 } 154 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 155 156 void crypto_put_default_rng(void) 157 { 158 mutex_lock(&crypto_default_rng_lock); 159 crypto_default_rng_refcnt--; 160 mutex_unlock(&crypto_default_rng_lock); 161 } 162 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 163 164 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE) 165 int crypto_del_default_rng(void) 166 { 167 int err = -EBUSY; 168 169 mutex_lock(&crypto_default_rng_lock); 170 if (crypto_default_rng_refcnt) 171 goto out; 172 173 crypto_free_rng(crypto_default_rng); 174 crypto_default_rng = NULL; 175 176 err = 0; 177 178 out: 179 mutex_unlock(&crypto_default_rng_lock); 180 181 return err; 182 } 183 EXPORT_SYMBOL_GPL(crypto_del_default_rng); 184 #endif 185 186 int crypto_register_rng(struct rng_alg *alg) 187 { 188 struct crypto_alg *base = &alg->base; 189 190 if (alg->seedsize > PAGE_SIZE / 8) 191 return -EINVAL; 192 193 base->cra_type = &crypto_rng_type; 194 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK; 195 base->cra_flags |= CRYPTO_ALG_TYPE_RNG; 196 197 return crypto_register_alg(base); 198 } 199 EXPORT_SYMBOL_GPL(crypto_register_rng); 200 201 void crypto_unregister_rng(struct rng_alg *alg) 202 { 203 crypto_unregister_alg(&alg->base); 204 } 205 EXPORT_SYMBOL_GPL(crypto_unregister_rng); 206 207 int crypto_register_rngs(struct rng_alg *algs, int count) 208 { 209 int i, ret; 210 211 for (i = 0; i < count; i++) { 212 ret = crypto_register_rng(algs + i); 213 if (ret) 214 goto err; 215 } 216 217 return 0; 218 219 err: 220 for (--i; i >= 0; --i) 221 crypto_unregister_rng(algs + i); 222 223 return ret; 224 } 225 EXPORT_SYMBOL_GPL(crypto_register_rngs); 226 227 void crypto_unregister_rngs(struct rng_alg *algs, int count) 228 { 229 int i; 230 231 for (i = count - 1; i >= 0; --i) 232 crypto_unregister_rng(algs + i); 233 } 234 EXPORT_SYMBOL_GPL(crypto_unregister_rngs); 235 236 MODULE_LICENSE("GPL"); 237 MODULE_DESCRIPTION("Random Number Generator"); 238