Root/crypto/rng.c

1/*
2 * Cryptographic API.
3 *
4 * RNG operations.
5 *
6 * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the Free
10 * Software Foundation; either version 2 of the License, or (at your option)
11 * any later version.
12 *
13 */
14
15#include <linux/atomic.h>
16#include <crypto/internal/rng.h>
17#include <linux/err.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20#include <linux/random.h>
21#include <linux/seq_file.h>
22#include <linux/slab.h>
23#include <linux/string.h>
24#include <linux/cryptouser.h>
25#include <net/netlink.h>
26
27static DEFINE_MUTEX(crypto_default_rng_lock);
28struct crypto_rng *crypto_default_rng;
29EXPORT_SYMBOL_GPL(crypto_default_rng);
30static int crypto_default_rng_refcnt;
31
32static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
33{
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        get_random_bytes(buf, slen);
43        seed = buf;
44    }
45
46    err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen);
47
48    kfree(buf);
49    return err;
50}
51
52static int crypto_init_rng_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
53{
54    struct rng_alg *alg = &tfm->__crt_alg->cra_rng;
55    struct rng_tfm *ops = &tfm->crt_rng;
56
57    ops->rng_gen_random = alg->rng_make_random;
58    ops->rng_reset = rngapi_reset;
59
60    return 0;
61}
62
63#ifdef CONFIG_NET
64static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
65{
66    struct crypto_report_rng rrng;
67
68    strncpy(rrng.type, "rng", sizeof(rrng.type));
69
70    rrng.seedsize = alg->cra_rng.seedsize;
71
72    if (nla_put(skb, CRYPTOCFGA_REPORT_RNG,
73            sizeof(struct crypto_report_rng), &rrng))
74        goto nla_put_failure;
75    return 0;
76
77nla_put_failure:
78    return -EMSGSIZE;
79}
80#else
81static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
82{
83    return -ENOSYS;
84}
85#endif
86
87static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
88    __attribute__ ((unused));
89static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
90{
91    seq_printf(m, "type : rng\n");
92    seq_printf(m, "seedsize : %u\n", alg->cra_rng.seedsize);
93}
94
95static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type,
96                       u32 mask)
97{
98    return alg->cra_ctxsize;
99}
100
101const struct crypto_type crypto_rng_type = {
102    .ctxsize = crypto_rng_ctxsize,
103    .init = crypto_init_rng_ops,
104#ifdef CONFIG_PROC_FS
105    .show = crypto_rng_show,
106#endif
107    .report = crypto_rng_report,
108};
109EXPORT_SYMBOL_GPL(crypto_rng_type);
110
111int crypto_get_default_rng(void)
112{
113    struct crypto_rng *rng;
114    int err;
115
116    mutex_lock(&crypto_default_rng_lock);
117    if (!crypto_default_rng) {
118        rng = crypto_alloc_rng("stdrng", 0, 0);
119        err = PTR_ERR(rng);
120        if (IS_ERR(rng))
121            goto unlock;
122
123        err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
124        if (err) {
125            crypto_free_rng(rng);
126            goto unlock;
127        }
128
129        crypto_default_rng = rng;
130    }
131
132    crypto_default_rng_refcnt++;
133    err = 0;
134
135unlock:
136    mutex_unlock(&crypto_default_rng_lock);
137
138    return err;
139}
140EXPORT_SYMBOL_GPL(crypto_get_default_rng);
141
142void crypto_put_default_rng(void)
143{
144    mutex_lock(&crypto_default_rng_lock);
145    if (!--crypto_default_rng_refcnt) {
146        crypto_free_rng(crypto_default_rng);
147        crypto_default_rng = NULL;
148    }
149    mutex_unlock(&crypto_default_rng_lock);
150}
151EXPORT_SYMBOL_GPL(crypto_put_default_rng);
152
153MODULE_LICENSE("GPL");
154MODULE_DESCRIPTION("Random Number Generator");
155

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