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 struct crypto_alg *alg = tfm->base.__crt_alg; 39 u8 *buf = NULL; 40 int err; 41 42 crypto_stats_get(alg); 43 if (!seed && slen) { 44 buf = kmalloc(slen, GFP_KERNEL); 45 if (!buf) 46 return -ENOMEM; 47 48 err = get_random_bytes_wait(buf, slen); 49 if (err) 50 goto out; 51 seed = buf; 52 } 53 54 err = crypto_rng_alg(tfm)->seed(tfm, seed, slen); 55 crypto_stats_rng_seed(alg, err); 56 out: 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 memset(&rrng, 0, sizeof(rrng)); 80 81 strscpy(rrng.type, "rng", sizeof(rrng.type)); 82 83 rrng.seedsize = seedsize(alg); 84 85 return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng); 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 __maybe_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", seedsize(alg)); 100 } 101 102 static 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 }; 114 115 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask) 116 { 117 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask); 118 } 119 EXPORT_SYMBOL_GPL(crypto_alloc_rng); 120 121 int crypto_get_default_rng(void) 122 { 123 struct crypto_rng *rng; 124 int err; 125 126 mutex_lock(&crypto_default_rng_lock); 127 if (!crypto_default_rng) { 128 rng = crypto_alloc_rng("stdrng", 0, 0); 129 err = PTR_ERR(rng); 130 if (IS_ERR(rng)) 131 goto unlock; 132 133 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 134 if (err) { 135 crypto_free_rng(rng); 136 goto unlock; 137 } 138 139 crypto_default_rng = rng; 140 } 141 142 crypto_default_rng_refcnt++; 143 err = 0; 144 145 unlock: 146 mutex_unlock(&crypto_default_rng_lock); 147 148 return err; 149 } 150 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 151 152 void crypto_put_default_rng(void) 153 { 154 mutex_lock(&crypto_default_rng_lock); 155 crypto_default_rng_refcnt--; 156 mutex_unlock(&crypto_default_rng_lock); 157 } 158 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 159 160 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE) 161 int crypto_del_default_rng(void) 162 { 163 int err = -EBUSY; 164 165 mutex_lock(&crypto_default_rng_lock); 166 if (crypto_default_rng_refcnt) 167 goto out; 168 169 crypto_free_rng(crypto_default_rng); 170 crypto_default_rng = NULL; 171 172 err = 0; 173 174 out: 175 mutex_unlock(&crypto_default_rng_lock); 176 177 return err; 178 } 179 EXPORT_SYMBOL_GPL(crypto_del_default_rng); 180 #endif 181 182 int crypto_register_rng(struct rng_alg *alg) 183 { 184 struct crypto_alg *base = &alg->base; 185 186 if (alg->seedsize > PAGE_SIZE / 8) 187 return -EINVAL; 188 189 base->cra_type = &crypto_rng_type; 190 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK; 191 base->cra_flags |= CRYPTO_ALG_TYPE_RNG; 192 193 return crypto_register_alg(base); 194 } 195 EXPORT_SYMBOL_GPL(crypto_register_rng); 196 197 void crypto_unregister_rng(struct rng_alg *alg) 198 { 199 crypto_unregister_alg(&alg->base); 200 } 201 EXPORT_SYMBOL_GPL(crypto_unregister_rng); 202 203 int crypto_register_rngs(struct rng_alg *algs, int count) 204 { 205 int i, ret; 206 207 for (i = 0; i < count; i++) { 208 ret = crypto_register_rng(algs + i); 209 if (ret) 210 goto err; 211 } 212 213 return 0; 214 215 err: 216 for (--i; i >= 0; --i) 217 crypto_unregister_rng(algs + i); 218 219 return ret; 220 } 221 EXPORT_SYMBOL_GPL(crypto_register_rngs); 222 223 void crypto_unregister_rngs(struct rng_alg *algs, int count) 224 { 225 int i; 226 227 for (i = count - 1; i >= 0; --i) 228 crypto_unregister_rng(algs + i); 229 } 230 EXPORT_SYMBOL_GPL(crypto_unregister_rngs); 231 232 MODULE_LICENSE("GPL"); 233 MODULE_DESCRIPTION("Random Number Generator"); 234