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 memset(&rrng, 0, sizeof(rrng)); 78 79 strscpy(rrng.type, "rng", sizeof(rrng.type)); 80 81 rrng.seedsize = seedsize(alg); 82 83 return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng); 84 } 85 #else 86 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 87 { 88 return -ENOSYS; 89 } 90 #endif 91 92 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 93 __maybe_unused; 94 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 95 { 96 seq_printf(m, "type : rng\n"); 97 seq_printf(m, "seedsize : %u\n", seedsize(alg)); 98 } 99 100 static const struct crypto_type crypto_rng_type = { 101 .extsize = crypto_alg_extsize, 102 .init_tfm = crypto_rng_init_tfm, 103 #ifdef CONFIG_PROC_FS 104 .show = crypto_rng_show, 105 #endif 106 .report = crypto_rng_report, 107 .maskclear = ~CRYPTO_ALG_TYPE_MASK, 108 .maskset = CRYPTO_ALG_TYPE_MASK, 109 .type = CRYPTO_ALG_TYPE_RNG, 110 .tfmsize = offsetof(struct crypto_rng, base), 111 }; 112 113 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask) 114 { 115 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask); 116 } 117 EXPORT_SYMBOL_GPL(crypto_alloc_rng); 118 119 int crypto_get_default_rng(void) 120 { 121 struct crypto_rng *rng; 122 int err; 123 124 mutex_lock(&crypto_default_rng_lock); 125 if (!crypto_default_rng) { 126 rng = crypto_alloc_rng("stdrng", 0, 0); 127 err = PTR_ERR(rng); 128 if (IS_ERR(rng)) 129 goto unlock; 130 131 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 132 if (err) { 133 crypto_free_rng(rng); 134 goto unlock; 135 } 136 137 crypto_default_rng = rng; 138 } 139 140 crypto_default_rng_refcnt++; 141 err = 0; 142 143 unlock: 144 mutex_unlock(&crypto_default_rng_lock); 145 146 return err; 147 } 148 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 149 150 void crypto_put_default_rng(void) 151 { 152 mutex_lock(&crypto_default_rng_lock); 153 crypto_default_rng_refcnt--; 154 mutex_unlock(&crypto_default_rng_lock); 155 } 156 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 157 158 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE) 159 int crypto_del_default_rng(void) 160 { 161 int err = -EBUSY; 162 163 mutex_lock(&crypto_default_rng_lock); 164 if (crypto_default_rng_refcnt) 165 goto out; 166 167 crypto_free_rng(crypto_default_rng); 168 crypto_default_rng = NULL; 169 170 err = 0; 171 172 out: 173 mutex_unlock(&crypto_default_rng_lock); 174 175 return err; 176 } 177 EXPORT_SYMBOL_GPL(crypto_del_default_rng); 178 #endif 179 180 int crypto_register_rng(struct rng_alg *alg) 181 { 182 struct crypto_alg *base = &alg->base; 183 184 if (alg->seedsize > PAGE_SIZE / 8) 185 return -EINVAL; 186 187 base->cra_type = &crypto_rng_type; 188 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK; 189 base->cra_flags |= CRYPTO_ALG_TYPE_RNG; 190 191 return crypto_register_alg(base); 192 } 193 EXPORT_SYMBOL_GPL(crypto_register_rng); 194 195 void crypto_unregister_rng(struct rng_alg *alg) 196 { 197 crypto_unregister_alg(&alg->base); 198 } 199 EXPORT_SYMBOL_GPL(crypto_unregister_rng); 200 201 int crypto_register_rngs(struct rng_alg *algs, int count) 202 { 203 int i, ret; 204 205 for (i = 0; i < count; i++) { 206 ret = crypto_register_rng(algs + i); 207 if (ret) 208 goto err; 209 } 210 211 return 0; 212 213 err: 214 for (--i; i >= 0; --i) 215 crypto_unregister_rng(algs + i); 216 217 return ret; 218 } 219 EXPORT_SYMBOL_GPL(crypto_register_rngs); 220 221 void crypto_unregister_rngs(struct rng_alg *algs, int count) 222 { 223 int i; 224 225 for (i = count - 1; i >= 0; --i) 226 crypto_unregister_rng(algs + i); 227 } 228 EXPORT_SYMBOL_GPL(crypto_unregister_rngs); 229 230 MODULE_LICENSE("GPL"); 231 MODULE_DESCRIPTION("Random Number Generator"); 232