| 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 | if (!seed && slen) { |
| 38 | buf = kmalloc(slen, GFP_KERNEL); |
| 39 | if (!buf) |
| 40 | return -ENOMEM; |
| 41 | |
| 42 | err = get_random_bytes_wait(buf, slen); |
| 43 | if (err) |
| 44 | goto out; |
| 45 | seed = buf; |
| 46 | } |
| 47 | |
| 48 | crypto_stats_get(alg); |
| 49 | err = crypto_rng_alg(tfm)->seed(tfm, seed, slen); |
| 50 | crypto_stats_rng_seed(alg, err); |
| 51 | out: |
| 52 | kfree_sensitive(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"); |