1 /* 2 * Cryptographic API. 3 * 4 * RNG operations. 5 * 6 * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com> 7 * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au> 8 * 9 * This program is free software; you can redistribute it and/or modify it 10 * under the terms of the GNU General Public License as published by the Free 11 * Software Foundation; either version 2 of the License, or (at your option) 12 * any later version. 13 * 14 */ 15 16 #include <linux/atomic.h> 17 #include <crypto/internal/rng.h> 18 #include <linux/err.h> 19 #include <linux/module.h> 20 #include <linux/mutex.h> 21 #include <linux/random.h> 22 #include <linux/seq_file.h> 23 #include <linux/slab.h> 24 #include <linux/string.h> 25 #include <linux/cryptouser.h> 26 #include <net/netlink.h> 27 28 #include "internal.h" 29 30 static DEFINE_MUTEX(crypto_default_rng_lock); 31 struct crypto_rng *crypto_default_rng; 32 EXPORT_SYMBOL_GPL(crypto_default_rng); 33 static int crypto_default_rng_refcnt; 34 35 static inline struct crypto_rng *__crypto_rng_cast(struct crypto_tfm *tfm) 36 { 37 return container_of(tfm, struct crypto_rng, base); 38 } 39 40 int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen) 41 { 42 u8 *buf = NULL; 43 int err; 44 45 if (!seed && slen) { 46 buf = kmalloc(slen, GFP_KERNEL); 47 if (!buf) 48 return -ENOMEM; 49 50 get_random_bytes(buf, slen); 51 seed = buf; 52 } 53 54 err = crypto_rng_alg(tfm)->seed(tfm, seed, slen); 55 56 kfree(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 strncpy(rrng.type, "rng", sizeof(rrng.type)); 79 80 rrng.seedsize = seedsize(alg); 81 82 if (nla_put(skb, CRYPTOCFGA_REPORT_RNG, 83 sizeof(struct crypto_report_rng), &rrng)) 84 goto nla_put_failure; 85 return 0; 86 87 nla_put_failure: 88 return -EMSGSIZE; 89 } 90 #else 91 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) 92 { 93 return -ENOSYS; 94 } 95 #endif 96 97 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 98 __attribute__ ((unused)); 99 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg) 100 { 101 seq_printf(m, "type : rng\n"); 102 seq_printf(m, "seedsize : %u\n", seedsize(alg)); 103 } 104 105 static const struct crypto_type crypto_rng_type = { 106 .extsize = crypto_alg_extsize, 107 .init_tfm = crypto_rng_init_tfm, 108 #ifdef CONFIG_PROC_FS 109 .show = crypto_rng_show, 110 #endif 111 .report = crypto_rng_report, 112 .maskclear = ~CRYPTO_ALG_TYPE_MASK, 113 .maskset = CRYPTO_ALG_TYPE_MASK, 114 .type = CRYPTO_ALG_TYPE_RNG, 115 .tfmsize = offsetof(struct crypto_rng, base), 116 }; 117 118 struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask) 119 { 120 return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask); 121 } 122 EXPORT_SYMBOL_GPL(crypto_alloc_rng); 123 124 int crypto_get_default_rng(void) 125 { 126 struct crypto_rng *rng; 127 int err; 128 129 mutex_lock(&crypto_default_rng_lock); 130 if (!crypto_default_rng) { 131 rng = crypto_alloc_rng("stdrng", 0, 0); 132 err = PTR_ERR(rng); 133 if (IS_ERR(rng)) 134 goto unlock; 135 136 err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng)); 137 if (err) { 138 crypto_free_rng(rng); 139 goto unlock; 140 } 141 142 crypto_default_rng = rng; 143 } 144 145 crypto_default_rng_refcnt++; 146 err = 0; 147 148 unlock: 149 mutex_unlock(&crypto_default_rng_lock); 150 151 return err; 152 } 153 EXPORT_SYMBOL_GPL(crypto_get_default_rng); 154 155 void crypto_put_default_rng(void) 156 { 157 mutex_lock(&crypto_default_rng_lock); 158 if (!--crypto_default_rng_refcnt) { 159 crypto_free_rng(crypto_default_rng); 160 crypto_default_rng = NULL; 161 } 162 mutex_unlock(&crypto_default_rng_lock); 163 } 164 EXPORT_SYMBOL_GPL(crypto_put_default_rng); 165 166 int crypto_register_rng(struct rng_alg *alg) 167 { 168 struct crypto_alg *base = &alg->base; 169 170 if (alg->seedsize > PAGE_SIZE / 8) 171 return -EINVAL; 172 173 base->cra_type = &crypto_rng_type; 174 base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK; 175 base->cra_flags |= CRYPTO_ALG_TYPE_RNG; 176 177 return crypto_register_alg(base); 178 } 179 EXPORT_SYMBOL_GPL(crypto_register_rng); 180 181 void crypto_unregister_rng(struct rng_alg *alg) 182 { 183 crypto_unregister_alg(&alg->base); 184 } 185 EXPORT_SYMBOL_GPL(crypto_unregister_rng); 186 187 int crypto_register_rngs(struct rng_alg *algs, int count) 188 { 189 int i, ret; 190 191 for (i = 0; i < count; i++) { 192 ret = crypto_register_rng(algs + i); 193 if (ret) 194 goto err; 195 } 196 197 return 0; 198 199 err: 200 for (--i; i >= 0; --i) 201 crypto_unregister_rng(algs + i); 202 203 return ret; 204 } 205 EXPORT_SYMBOL_GPL(crypto_register_rngs); 206 207 void crypto_unregister_rngs(struct rng_alg *algs, int count) 208 { 209 int i; 210 211 for (i = count - 1; i >= 0; --i) 212 crypto_unregister_rng(algs + i); 213 } 214 EXPORT_SYMBOL_GPL(crypto_unregister_rngs); 215 216 MODULE_LICENSE("GPL"); 217 MODULE_DESCRIPTION("Random Number Generator"); 218