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 static struct crypto_rng *crypto_default_rng; 28 static int crypto_default_rng_refcnt; 29 30 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen) 31 { 32 u8 *buf = NULL; 33 int err; 34 35 if (!seed && slen) { 36 buf = kmalloc(slen, GFP_KERNEL); 37 if (!buf) 38 return -ENOMEM; 39 40 err = get_random_bytes_wait(buf, slen); 41 if (err) 42 goto out; 43 seed = buf; 44 } 45 46 err = crypto_rng_alg(tfm)->seed(tfm, seed, slen); 47 out: 48 kfree_sensitive(buf); 49 return err; 50 } 51 EXPORT_SYMBOL_GPL(crypto_rng_reset); 52 53 static int crypto_rng_init_tfm(struct crypto_tfm *tfm) 54 { 55 return 0; 56 } 57 58 static unsigned int seedsize(struct crypto_alg *alg) 59 { 60 struct rng_alg *ralg = container_of(alg, struct rng_alg, base); 61 62 return ralg->seedsize; 63 } 64 65 static int __maybe_unused crypto_rng_report( 66 struct sk_buff *skb, struct crypto_alg *alg) 67 { 68 struct crypto_report_rng rrng; 69 70 memset(&rrng, 0, sizeof(rrng)); 71 72 strscpy(rrng.type, "rng", sizeof(rrng.type)); 73 74 rrng.seedsize = seedsize(alg); 75 76 return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng); 77 } 78 79 static void __maybe_unused crypto_rng_show(struct seq_file *m, 80 struct crypto_alg *alg) 81 { 82 seq_printf(m, "type : rng\n"); 83 seq_printf(m, "seedsize : %u\n", seedsize(alg)); 84 } 85 86 static const struct crypto_type crypto_rng_type = { 87 .extsize = crypto_alg_extsize, 88 .init_tfm = crypto_rng_init_tfm, 89 #ifdef CONFIG_PROC_FS 90 .show = crypto_rng_show, 91 #endif 92 #if IS_ENABLED(CONFIG_CRYPTO_USER) 93 .report = crypto_rng_report, 94 #endif 95 .maskclear = ~CRYPTO_ALG_TYPE_MASK, 96 .maskset = CRYPTO_ALG_TYPE_MASK, 97 .type = CRYPTO_ALG_TYPE_RNG, 98 .tfmsize = offsetof(struct crypto_rng, base), 99 .algsize = offsetof(struct rng_alg, base), 100 }; 101 102 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask) 103 { 104 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask); 105 } 106 EXPORT_SYMBOL_GPL(crypto_alloc_rng); 107 108 static int crypto_get_default_rng(void) 109 { 110 struct crypto_rng *rng; 111 int err; 112 113 mutex_lock(&crypto_default_rng_lock); 114 if (!crypto_default_rng) { 115 rng = crypto_alloc_rng("stdrng", 0, 0); 116 err = PTR_ERR(rng); 117 if (IS_ERR(rng)) 118 goto unlock; 119 120 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 121 if (err) { 122 crypto_free_rng(rng); 123 goto unlock; 124 } 125 126 crypto_default_rng = rng; 127 } 128 129 crypto_default_rng_refcnt++; 130 err = 0; 131 132 unlock: 133 mutex_unlock(&crypto_default_rng_lock); 134 135 return err; 136 } 137 138 static void crypto_put_default_rng(void) 139 { 140 mutex_lock(&crypto_default_rng_lock); 141 crypto_default_rng_refcnt--; 142 mutex_unlock(&crypto_default_rng_lock); 143 } 144 145 int __crypto_stdrng_get_bytes(void *buf, unsigned int len) 146 { 147 int err; 148 149 err = crypto_get_default_rng(); 150 if (err) 151 return err; 152 153 err = crypto_rng_get_bytes(crypto_default_rng, buf, len); 154 crypto_put_default_rng(); 155 return err; 156 } 157 EXPORT_SYMBOL_GPL(__crypto_stdrng_get_bytes); 158 159 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE) 160 int crypto_del_default_rng(void) 161 { 162 int err = -EBUSY; 163 164 mutex_lock(&crypto_default_rng_lock); 165 if (crypto_default_rng_refcnt) 166 goto out; 167 168 crypto_free_rng(crypto_default_rng); 169 crypto_default_rng = NULL; 170 171 err = 0; 172 173 out: 174 mutex_unlock(&crypto_default_rng_lock); 175 176 return err; 177 } 178 EXPORT_SYMBOL_GPL(crypto_del_default_rng); 179 #endif 180 181 static void rng_default_set_ent(struct crypto_rng *tfm, const u8 *data, 182 unsigned int len) 183 { 184 } 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 if (!alg->set_ent) 198 alg->set_ent = rng_default_set_ent; 199 200 return crypto_register_alg(base); 201 } 202 EXPORT_SYMBOL_GPL(crypto_register_rng); 203 204 void crypto_unregister_rng(struct rng_alg *alg) 205 { 206 crypto_unregister_alg(&alg->base); 207 } 208 EXPORT_SYMBOL_GPL(crypto_unregister_rng); 209 210 int crypto_register_rngs(struct rng_alg *algs, int count) 211 { 212 int i, ret; 213 214 for (i = 0; i < count; i++) { 215 ret = crypto_register_rng(algs + i); 216 if (ret) { 217 crypto_unregister_rngs(algs, i); 218 return ret; 219 } 220 } 221 222 return 0; 223 } 224 EXPORT_SYMBOL_GPL(crypto_register_rngs); 225 226 void crypto_unregister_rngs(struct rng_alg *algs, int count) 227 { 228 int i; 229 230 for (i = count - 1; i >= 0; --i) 231 crypto_unregister_rng(algs + i); 232 } 233 EXPORT_SYMBOL_GPL(crypto_unregister_rngs); 234 235 MODULE_LICENSE("GPL"); 236 MODULE_DESCRIPTION("Random Number Generator"); 237