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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 | |
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 | |
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 |
64 | static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg) |
65 | { |
66 | struct crypto_report_rng rrng; |
67 | |
68 | snprintf(rrng.type, CRYPTO_MAX_ALG_NAME, "%s", "rng"); |
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 |
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)); |
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 | |
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 | |
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 | |
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 |
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