xref: /openbmc/linux/crypto/rng.c (revision 285e74ab4f94d921a56fcf66320b3cd65e35b6bc)
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