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 <linux/atomic.h> 12 #include <crypto/internal/rng.h> 13 #include <linux/err.h> 14 #include <linux/module.h> 15 #include <linux/mutex.h> 16 #include <linux/random.h> 17 #include <linux/seq_file.h> 18 #include <linux/slab.h> 19 #include <linux/string.h> 20 #include <linux/cryptouser.h> 21 #include <linux/compiler.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 struct crypto_alg *alg = tfm->base.__crt_alg; 34 u8 *buf = NULL; 35 int err; 36 37 crypto_stats_get(alg); 38 if (!seed && slen) { 39 buf = kmalloc(slen, GFP_KERNEL); 40 if (!buf) { 41 crypto_alg_put(alg); 42 return -ENOMEM; 43 } 44 45 err = get_random_bytes_wait(buf, slen); 46 if (err) { 47 crypto_alg_put(alg); 48 goto out; 49 } 50 seed = buf; 51 } 52 53 err = crypto_rng_alg(tfm)->seed(tfm, seed, slen); 54 crypto_stats_rng_seed(alg, err); 55 out: 56 kzfree(buf); 57 return err; 58 } 59 EXPORT_SYMBOL_GPL(crypto_rng_reset); 60 61 static int crypto_rng_init_tfm(struct crypto_tfm *tfm) 62 { 63 return 0; 64 } 65 66 static unsigned int seedsize(struct crypto_alg *alg) 67 { 68 struct rng_alg *ralg = container_of(alg, struct rng_alg, base); 69 70 return ralg->seedsize; 71 } 72 73 #ifdef CONFIG_NET 74 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 75 { 76 struct crypto_report_rng rrng; 77 78 memset(&rrng, 0, sizeof(rrng)); 79 80 strscpy(rrng.type, "rng", sizeof(rrng.type)); 81 82 rrng.seedsize = seedsize(alg); 83 84 return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng); 85 } 86 #else 87 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 88 { 89 return -ENOSYS; 90 } 91 #endif 92 93 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 94 __maybe_unused; 95 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 96 { 97 seq_printf(m, "type : rng\n"); 98 seq_printf(m, "seedsize : %u\n", seedsize(alg)); 99 } 100 101 static const struct crypto_type crypto_rng_type = { 102 .extsize = crypto_alg_extsize, 103 .init_tfm = crypto_rng_init_tfm, 104 #ifdef CONFIG_PROC_FS 105 .show = crypto_rng_show, 106 #endif 107 .report = crypto_rng_report, 108 .maskclear = ~CRYPTO_ALG_TYPE_MASK, 109 .maskset = CRYPTO_ALG_TYPE_MASK, 110 .type = CRYPTO_ALG_TYPE_RNG, 111 .tfmsize = offsetof(struct crypto_rng, base), 112 }; 113 114 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask) 115 { 116 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask); 117 } 118 EXPORT_SYMBOL_GPL(crypto_alloc_rng); 119 120 int crypto_get_default_rng(void) 121 { 122 struct crypto_rng *rng; 123 int err; 124 125 mutex_lock(&crypto_default_rng_lock); 126 if (!crypto_default_rng) { 127 rng = crypto_alloc_rng("stdrng", 0, 0); 128 err = PTR_ERR(rng); 129 if (IS_ERR(rng)) 130 goto unlock; 131 132 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 133 if (err) { 134 crypto_free_rng(rng); 135 goto unlock; 136 } 137 138 crypto_default_rng = rng; 139 } 140 141 crypto_default_rng_refcnt++; 142 err = 0; 143 144 unlock: 145 mutex_unlock(&crypto_default_rng_lock); 146 147 return err; 148 } 149 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 150 151 void crypto_put_default_rng(void) 152 { 153 mutex_lock(&crypto_default_rng_lock); 154 crypto_default_rng_refcnt--; 155 mutex_unlock(&crypto_default_rng_lock); 156 } 157 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 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 int crypto_register_rng(struct rng_alg *alg) 182 { 183 struct crypto_alg *base = &alg->base; 184 185 if (alg->seedsize > PAGE_SIZE / 8) 186 return -EINVAL; 187 188 base->cra_type = &crypto_rng_type; 189 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK; 190 base->cra_flags |= CRYPTO_ALG_TYPE_RNG; 191 192 return crypto_register_alg(base); 193 } 194 EXPORT_SYMBOL_GPL(crypto_register_rng); 195 196 void crypto_unregister_rng(struct rng_alg *alg) 197 { 198 crypto_unregister_alg(&alg->base); 199 } 200 EXPORT_SYMBOL_GPL(crypto_unregister_rng); 201 202 int crypto_register_rngs(struct rng_alg *algs, int count) 203 { 204 int i, ret; 205 206 for (i = 0; i < count; i++) { 207 ret = crypto_register_rng(algs + i); 208 if (ret) 209 goto err; 210 } 211 212 return 0; 213 214 err: 215 for (--i; i >= 0; --i) 216 crypto_unregister_rng(algs + i); 217 218 return ret; 219 } 220 EXPORT_SYMBOL_GPL(crypto_register_rngs); 221 222 void crypto_unregister_rngs(struct rng_alg *algs, int count) 223 { 224 int i; 225 226 for (i = count - 1; i >= 0; --i) 227 crypto_unregister_rng(algs + i); 228 } 229 EXPORT_SYMBOL_GPL(crypto_unregister_rngs); 230 231 MODULE_LICENSE("GPL"); 232 MODULE_DESCRIPTION("Random Number Generator"); 233