summaryrefslogtreecommitdiffstats
path: root/crypto/rng.c
blob: 4514d3755f7941a416e6b5fbfc66e1e65b6b750c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
/*
 * Cryptographic API.
 *
 * RNG operations.
 *
 * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */

#include <linux/atomic.h>
#include <crypto/internal/rng.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/random.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/cryptouser.h>
#include <net/netlink.h>

#include "internal.h"

static DEFINE_MUTEX(crypto_default_rng_lock);
struct crypto_rng *crypto_default_rng;
EXPORT_SYMBOL_GPL(crypto_default_rng);
static int crypto_default_rng_refcnt;

static inline struct crypto_rng *__crypto_rng_cast(struct crypto_tfm *tfm)
{
	return container_of(tfm, struct crypto_rng, base);
}

static int generate(struct crypto_rng *tfm, const u8 *src, unsigned int slen,
		    u8 *dst, unsigned int dlen)
{
	return crypto_rng_alg(tfm)->rng_make_random(tfm, dst, dlen);
}

static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
{
	u8 *buf = NULL;
	int err;

	if (!seed && slen) {
		buf = kmalloc(slen, GFP_KERNEL);
		if (!buf)
			return -ENOMEM;

		get_random_bytes(buf, slen);
		seed = buf;
	}

	err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen);

	kfree(buf);
	return err;
}

static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
{
	struct crypto_rng *rng = __crypto_rng_cast(tfm);

	rng->generate = generate;
	rng->seed = rngapi_reset;

	return 0;
}

#ifdef CONFIG_NET
static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
{
	struct crypto_report_rng rrng;

	strncpy(rrng.type, "rng", sizeof(rrng.type));

	rrng.seedsize = alg->cra_rng.seedsize;

	if (nla_put(skb, CRYPTOCFGA_REPORT_RNG,
		    sizeof(struct crypto_report_rng), &rrng))
		goto nla_put_failure;
	return 0;

nla_put_failure:
	return -EMSGSIZE;
}
#else
static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
{
	return -ENOSYS;
}
#endif

static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
	__attribute__ ((unused));
static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
{
	seq_printf(m, "type         : rng\n");
	seq_printf(m, "seedsize     : %u\n", alg->cra_rng.seedsize);
}

const struct crypto_type crypto_rng_type = {
	.extsize = crypto_alg_extsize,
	.init_tfm = crypto_rng_init_tfm,
#ifdef CONFIG_PROC_FS
	.show = crypto_rng_show,
#endif
	.report = crypto_rng_report,
	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
	.maskset = CRYPTO_ALG_TYPE_MASK,
	.type = CRYPTO_ALG_TYPE_RNG,
	.tfmsize = offsetof(struct crypto_rng, base),
};
EXPORT_SYMBOL_GPL(crypto_rng_type);

struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
{
	return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_rng);

int crypto_get_default_rng(void)
{
	struct crypto_rng *rng;
	int err;

	mutex_lock(&crypto_default_rng_lock);
	if (!crypto_default_rng) {
		rng = crypto_alloc_rng("stdrng", 0, 0);
		err = PTR_ERR(rng);
		if (IS_ERR(rng))
			goto unlock;

		err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
		if (err) {
			crypto_free_rng(rng);
			goto unlock;
		}

		crypto_default_rng = rng;
	}

	crypto_default_rng_refcnt++;
	err = 0;

unlock:
	mutex_unlock(&crypto_default_rng_lock);

	return err;
}
EXPORT_SYMBOL_GPL(crypto_get_default_rng);

void crypto_put_default_rng(void)
{
	mutex_lock(&crypto_default_rng_lock);
	if (!--crypto_default_rng_refcnt) {
		crypto_free_rng(crypto_default_rng);
		crypto_default_rng = NULL;
	}
	mutex_unlock(&crypto_default_rng_lock);
}
EXPORT_SYMBOL_GPL(crypto_put_default_rng);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Random Number Generator");