2 * algif_rng: User-space interface for random number generators
4 * This file provides the user-space API for random number generators.
6 * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de>
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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17 * 3. The name of the author may not be used to endorse or promote
18 * products derived from this software without specific prior
21 * ALTERNATIVELY, this product may be distributed under the terms of
22 * the GNU General Public License, in which case the provisions of the GPL2
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24 * necessary due to a potential bad interaction between the GPL and
25 * the restrictions contained in a BSD-style copyright.)
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41 #include <linux/module.h>
42 #include <crypto/rng.h>
43 #include <linux/random.h>
44 #include <crypto/if_alg.h>
45 #include <linux/net.h>
48 MODULE_LICENSE("GPL");
49 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
50 MODULE_DESCRIPTION("User-space interface for random number generators");
55 struct crypto_rng *drng;
58 static int rng_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
61 struct sock *sk = sock->sk;
62 struct alg_sock *ask = alg_sk(sk);
63 struct rng_ctx *ctx = ask->private;
74 * although not strictly needed, this is a precaution against coding
77 memset(result, 0, len);
80 * The enforcement of a proper seeding of an RNG is done within an
81 * RNG implementation. Some RNGs (DRBG, krng) do not need specific
82 * seeding as they automatically seed. The X9.31 DRNG will return
83 * an error if it was not seeded properly.
85 genlen = crypto_rng_get_bytes(ctx->drng, result, len);
89 err = memcpy_to_msg(msg, result, len);
90 memzero_explicit(result, len);
92 return err ? err : len;
95 static struct proto_ops algif_rng_ops = {
98 .connect = sock_no_connect,
99 .socketpair = sock_no_socketpair,
100 .getname = sock_no_getname,
101 .ioctl = sock_no_ioctl,
102 .listen = sock_no_listen,
103 .shutdown = sock_no_shutdown,
104 .mmap = sock_no_mmap,
105 .bind = sock_no_bind,
106 .accept = sock_no_accept,
107 .sendmsg = sock_no_sendmsg,
108 .sendpage = sock_no_sendpage,
110 .release = af_alg_release,
111 .recvmsg = rng_recvmsg,
114 static void *rng_bind(const char *name, u32 type, u32 mask)
116 return crypto_alloc_rng(name, type, mask);
119 static void rng_release(void *private)
121 crypto_free_rng(private);
124 static void rng_sock_destruct(struct sock *sk)
126 struct alg_sock *ask = alg_sk(sk);
127 struct rng_ctx *ctx = ask->private;
129 sock_kfree_s(sk, ctx, ctx->len);
130 af_alg_release_parent(sk);
133 static int rng_accept_parent(void *private, struct sock *sk)
136 struct alg_sock *ask = alg_sk(sk);
137 unsigned int len = sizeof(*ctx);
139 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
146 * No seeding done at that point -- if multiple accepts are
147 * done on one RNG instance, each resulting FD points to the same
153 sk->sk_destruct = rng_sock_destruct;
158 static int rng_setkey(void *private, const u8 *seed, unsigned int seedlen)
161 * Check whether seedlen is of sufficient size is done in RNG
164 return crypto_rng_reset(private, seed, seedlen);
167 static const struct af_alg_type algif_type_rng = {
169 .release = rng_release,
170 .accept = rng_accept_parent,
171 .setkey = rng_setkey,
172 .ops = &algif_rng_ops,
177 static int __init rng_init(void)
179 return af_alg_register_type(&algif_type_rng);
182 static void __exit rng_exit(void)
184 int err = af_alg_unregister_type(&algif_type_rng);
188 module_init(rng_init);
189 module_exit(rng_exit);