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 return -ENOMEM; 42 43 err = get_random_bytes_wait(buf, slen); 44 if (err) 45 goto out; 46 seed = buf; 47 } 48 49 err = crypto_rng_alg(tfm)->seed(tfm, seed, slen); 50 crypto_stats_rng_seed(alg, err); 51 out: 52 kzfree(buf); 53 return err; 54 } 55 EXPORT_SYMBOL_GPL(crypto_rng_reset); 56 57 static int crypto_rng_init_tfm(struct crypto_tfm *tfm) 58 { 59 return 0; 60 } 61 62 static unsigned int seedsize(struct crypto_alg *alg) 63 { 64 struct rng_alg *ralg = container_of(alg, struct rng_alg, base); 65 66 return ralg->seedsize; 67 } 68 69 #ifdef CONFIG_NET 70 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 71 { 72 struct crypto_report_rng rrng; 73 74 memset(&rrng, 0, sizeof(rrng)); 75 76 strscpy(rrng.type, "rng", sizeof(rrng.type)); 77 78 rrng.seedsize = seedsize(alg); 79 80 return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng); 81 } 82 #else 83 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 84 { 85 return -ENOSYS; 86 } 87 #endif 88 89 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 90 __maybe_unused; 91 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 92 { 93 seq_printf(m, "type : rng\n"); 94 seq_printf(m, "seedsize : %u\n", seedsize(alg)); 95 } 96 97 static const struct crypto_type crypto_rng_type = { 98 .extsize = crypto_alg_extsize, 99 .init_tfm = crypto_rng_init_tfm, 100 #ifdef CONFIG_PROC_FS 101 .show = crypto_rng_show, 102 #endif 103 .report = crypto_rng_report, 104 .maskclear = ~CRYPTO_ALG_TYPE_MASK, 105 .maskset = CRYPTO_ALG_TYPE_MASK, 106 .type = CRYPTO_ALG_TYPE_RNG, 107 .tfmsize = offsetof(struct crypto_rng, base), 108 }; 109 110 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask) 111 { 112 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask); 113 } 114 EXPORT_SYMBOL_GPL(crypto_alloc_rng); 115 116 int crypto_get_default_rng(void) 117 { 118 struct crypto_rng *rng; 119 int err; 120 121 mutex_lock(&crypto_default_rng_lock); 122 if (!crypto_default_rng) { 123 rng = crypto_alloc_rng("stdrng", 0, 0); 124 err = PTR_ERR(rng); 125 if (IS_ERR(rng)) 126 goto unlock; 127 128 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 129 if (err) { 130 crypto_free_rng(rng); 131 goto unlock; 132 } 133 134 crypto_default_rng = rng; 135 } 136 137 crypto_default_rng_refcnt++; 138 err = 0; 139 140 unlock: 141 mutex_unlock(&crypto_default_rng_lock); 142 143 return err; 144 } 145 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 146 147 void crypto_put_default_rng(void) 148 { 149 mutex_lock(&crypto_default_rng_lock); 150 crypto_default_rng_refcnt--; 151 mutex_unlock(&crypto_default_rng_lock); 152 } 153 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 154 155 #if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE) 156 int crypto_del_default_rng(void) 157 { 158 int err = -EBUSY; 159 160 mutex_lock(&crypto_default_rng_lock); 161 if (crypto_default_rng_refcnt) 162 goto out; 163 164 crypto_free_rng(crypto_default_rng); 165 crypto_default_rng = NULL; 166 167 err = 0; 168 169 out: 170 mutex_unlock(&crypto_default_rng_lock); 171 172 return err; 173 } 174 EXPORT_SYMBOL_GPL(crypto_del_default_rng); 175 #endif 176 177 int crypto_register_rng(struct rng_alg *alg) 178 { 179 struct crypto_alg *base = &alg->base; 180 181 if (alg->seedsize > PAGE_SIZE / 8) 182 return -EINVAL; 183 184 base->cra_type = &crypto_rng_type; 185 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK; 186 base->cra_flags |= CRYPTO_ALG_TYPE_RNG; 187 188 return crypto_register_alg(base); 189 } 190 EXPORT_SYMBOL_GPL(crypto_register_rng); 191 192 void crypto_unregister_rng(struct rng_alg *alg) 193 { 194 crypto_unregister_alg(&alg->base); 195 } 196 EXPORT_SYMBOL_GPL(crypto_unregister_rng); 197 198 int crypto_register_rngs(struct rng_alg *algs, int count) 199 { 200 int i, ret; 201 202 for (i = 0; i < count; i++) { 203 ret = crypto_register_rng(algs + i); 204 if (ret) 205 goto err; 206 } 207 208 return 0; 209 210 err: 211 for (--i; i >= 0; --i) 212 crypto_unregister_rng(algs + i); 213 214 return ret; 215 } 216 EXPORT_SYMBOL_GPL(crypto_register_rngs); 217 218 void crypto_unregister_rngs(struct rng_alg *algs, int count) 219 { 220 int i; 221 222 for (i = count - 1; i >= 0; --i) 223 crypto_unregister_rng(algs + i); 224 } 225 EXPORT_SYMBOL_GPL(crypto_unregister_rngs); 226 227 MODULE_LICENSE("GPL"); 228 MODULE_DESCRIPTION("Random Number Generator"); 229