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
27 static DEFINE_MUTEX(crypto_default_rng_lock);
28 struct crypto_rng *crypto_default_rng;
29 EXPORT_SYMBOL_GPL(crypto_default_rng);
30 static int crypto_default_rng_refcnt;
31
rngapi_reset(struct crypto_rng * tfm,u8 * seed,unsigned int slen)32 static 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
crypto_init_rng_ops(struct crypto_tfm * tfm,u32 type,u32 mask)52 static 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
crypto_rng_report(struct sk_buff * skb,struct crypto_alg * alg)64 static 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 NLA_PUT(skb, CRYPTOCFGA_REPORT_RNG,
73 sizeof(struct crypto_report_rng), &rrng);
74
75 return 0;
76
77 nla_put_failure:
78 return -EMSGSIZE;
79 }
80 #else
crypto_rng_report(struct sk_buff * skb,struct crypto_alg * alg)81 static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
82 {
83 return -ENOSYS;
84 }
85 #endif
86
87 static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
88 __attribute__ ((unused));
crypto_rng_show(struct seq_file * m,struct crypto_alg * alg)89 static 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
crypto_rng_ctxsize(struct crypto_alg * alg,u32 type,u32 mask)95 static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type,
96 u32 mask)
97 {
98 return alg->cra_ctxsize;
99 }
100
101 const 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 };
109 EXPORT_SYMBOL_GPL(crypto_rng_type);
110
crypto_get_default_rng(void)111 int 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
135 unlock:
136 mutex_unlock(&crypto_default_rng_lock);
137
138 return err;
139 }
140 EXPORT_SYMBOL_GPL(crypto_get_default_rng);
141
crypto_put_default_rng(void)142 void 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 }
151 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
152
153 MODULE_LICENSE("GPL");
154 MODULE_DESCRIPTION("Random Number Generator");
155