1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Cryptographic API. 4 * 5 * RNG operations. 6 * 7 * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com> 8 * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au> 9 */ 10 11 #include <crypto/internal/rng.h> 12 #include <linux/atomic.h> 13 #include <linux/cryptouser.h> 14 #include <linux/err.h> 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/mutex.h> 18 #include <linux/random.h> 19 #include <linux/seq_file.h> 20 #include <linux/slab.h> 21 #include <linux/string.h> 22 #include <net/netlink.h> 23 24 #include "internal.h" 25 26 static DEFINE_MUTEX(crypto_default_rng_lock); 27 struct crypto_rng *crypto_default_rng; 28 EXPORT_SYMBOL_GPL(crypto_default_rng); 29 static int crypto_default_rng_refcnt; 30 31 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen) 32 { 33 u8 *buf = NULL; 34 int err; 35 36 if (!seed && slen) { 37 buf = kmalloc(slen, GFP_KERNEL); 38 if (!buf) 39 return -ENOMEM; 40 41 err = get_random_bytes_wait(buf, slen); 42 if (err) 43 goto out; 44 seed = buf; 45 } 46 47 err = crypto_rng_alg(tfm)->seed(tfm, seed, slen); 48 out: 49 kfree_sensitive(buf); 50 return err; 51 } 52 EXPORT_SYMBOL_GPL(crypto_rng_reset); 53 54 static int crypto_rng_init_tfm(struct crypto_tfm *tfm) 55 { 56 return 0; 57 } 58 59 static unsigned int seedsize(struct crypto_alg *alg) 60 { 61 struct rng_alg *ralg = container_of(alg, struct rng_alg, base); 62 63 return ralg->seedsize; 64 } 65 66 static int __maybe_unused crypto_rng_report( 67 struct sk_buff *skb, struct crypto_alg *alg) 68 { 69 struct crypto_report_rng rrng; 70 71 memset(&rrng, 0, sizeof(rrng)); 72 73 strscpy(rrng.type, "rng", sizeof(rrng.type)); 74 75 rrng.seedsize = seedsize(alg); 76 77 return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng); 78 } 79 80 static void __maybe_unused crypto_rng_show(struct seq_file *m, 81 struct crypto_alg *alg) 82 { 83 seq_printf(m, "type : rng\n"); 84 seq_printf(m, "seedsize : %u\n", seedsize(alg)); 85 } 86 87 static const struct crypto_type crypto_rng_type = { 88 .extsize = crypto_alg_extsize, 89 .init_tfm = crypto_rng_init_tfm, 90 #ifdef CONFIG_PROC_FS 91 .show = crypto_rng_show, 92 #endif 93 #if IS_ENABLED(CONFIG_CRYPTO_USER) 94 .report = crypto_rng_report, 95 #endif 96 .maskclear = ~CRYPTO_ALG_TYPE_MASK, 97 .maskset = CRYPTO_ALG_TYPE_MASK, 98 .type = CRYPTO_ALG_TYPE_RNG, 99 .tfmsize = offsetof(struct crypto_rng, base), 100 .algsize = offsetof(struct rng_alg, base), 101 }; 102 103 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask) 104 { 105 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask); 106 } 107 EXPORT_SYMBOL_GPL(crypto_alloc_rng); 108 109 int crypto_get_default_rng(void) 110 { 111 struct crypto_rng *rng; 112 int err; 113 114 mutex_lock(&crypto_default_rng_lock); 115 if (!crypto_default_rng) { 116 rng = crypto_alloc_rng("stdrng", 0, 0); 117 err = PTR_ERR(rng); 118 if (IS_ERR(rng)) 119 goto unlock; 120 121 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 122 if (err) { 123 crypto_free_rng(rng); 124 goto unlock; 125 } 126 127 crypto_default_rng = rng; 128 } 129 130 crypto_default_rng_refcnt++; 131 err = 0; 132 133 unlock: 134 mutex_unlock(&crypto_default_rng_lock); 135 136 return err; 137 } 138 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 139 140 void crypto_put_default_rng(void) 141 { 142 mutex_lock(&crypto_default_rng_lock); 143 crypto_default_rng_refcnt--; 144 mutex_unlock(&crypto_default_rng_lock); 145 } 146 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 147 148 int crypto_stdrng_get_bytes(void *buf, unsigned int len) 149 { 150 int err; 151 152 err = crypto_get_default_rng(); 153 if (err) 154 return err; 155 156 err = crypto_rng_get_bytes(crypto_default_rng, buf, len); 157 crypto_put_default_rng(); 158 return err; 159 } 160 EXPORT_SYMBOL_GPL(crypto_stdrng_get_bytes); 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 static void rng_default_set_ent(struct crypto_rng *tfm, const u8 *data, 185 unsigned int len) 186 { 187 } 188 189 int crypto_register_rng(struct rng_alg *alg) 190 { 191 struct crypto_alg *base = &alg->base; 192 193 if (alg->seedsize > PAGE_SIZE / 8) 194 return -EINVAL; 195 196 base->cra_type = &crypto_rng_type; 197 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK; 198 base->cra_flags |= CRYPTO_ALG_TYPE_RNG; 199 200 if (!alg->set_ent) 201 alg->set_ent = rng_default_set_ent; 202 203 return crypto_register_alg(base); 204 } 205 EXPORT_SYMBOL_GPL(crypto_register_rng); 206 207 void crypto_unregister_rng(struct rng_alg *alg) 208 { 209 crypto_unregister_alg(&alg->base); 210 } 211 EXPORT_SYMBOL_GPL(crypto_unregister_rng); 212 213 int crypto_register_rngs(struct rng_alg *algs, int count) 214 { 215 int i, ret; 216 217 for (i = 0; i < count; i++) { 218 ret = crypto_register_rng(algs + i); 219 if (ret) { 220 crypto_unregister_rngs(algs, i); 221 return ret; 222 } 223 } 224 225 return 0; 226 } 227 EXPORT_SYMBOL_GPL(crypto_register_rngs); 228 229 void crypto_unregister_rngs(struct rng_alg *algs, int count) 230 { 231 int i; 232 233 for (i = count - 1; i >= 0; --i) 234 crypto_unregister_rng(algs + i); 235 } 236 EXPORT_SYMBOL_GPL(crypto_unregister_rngs); 237 238 MODULE_LICENSE("GPL"); 239 MODULE_DESCRIPTION("Random Number Generator"); 240