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| -rw-r--r-- | crypto/algif_rng.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/crypto/algif_rng.c b/crypto/algif_rng.c new file mode 100644 index 000000000000..91c06f5673dd --- /dev/null +++ b/crypto/algif_rng.c @@ -0,0 +1,192 @@ +/* + * algif_rng: User-space interface for random number generators + * + * This file provides the user-space API for random number generators. + * + * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, and the entire permission notice in its entirety, + * including the disclaimer of warranties. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote + * products derived from this software without specific prior + * written permission. + * + * ALTERNATIVELY, this product may be distributed under the terms of + * the GNU General Public License, in which case the provisions of the GPL2 + * are required INSTEAD OF the above restrictions. (This clause is + * necessary due to a potential bad interaction between the GPL and + * the restrictions contained in a BSD-style copyright.) + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF + * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT + * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR + * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE + * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH + * DAMAGE. + */ + +#include <linux/module.h> +#include <crypto/rng.h> +#include <linux/random.h> +#include <crypto/if_alg.h> +#include <linux/net.h> +#include <net/sock.h> + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>"); +MODULE_DESCRIPTION("User-space interface for random number generators"); + +struct rng_ctx { +#define MAXSIZE 128 + unsigned int len; + struct crypto_rng *drng; +}; + +static int rng_recvmsg(struct kiocb *unused, struct socket *sock, + struct msghdr *msg, size_t len, int flags) +{ + struct sock *sk = sock->sk; + struct alg_sock *ask = alg_sk(sk); + struct rng_ctx *ctx = ask->private; + int err = -EFAULT; + int genlen = 0; + u8 result[MAXSIZE]; + + if (len == 0) + return 0; + if (len > MAXSIZE) + len = MAXSIZE; + + /* + * although not strictly needed, this is a precaution against coding + * errors + */ + memset(result, 0, len); + + /* + * The enforcement of a proper seeding of an RNG is done within an + * RNG implementation. Some RNGs (DRBG, krng) do not need specific + * seeding as they automatically seed. The X9.31 DRNG will return + * an error if it was not seeded properly. + */ + genlen = crypto_rng_get_bytes(ctx->drng, result, len); + if (genlen < 0) + return genlen; + + err = memcpy_to_msg(msg, result, len); + memzero_explicit(result, genlen); + + return err ? err : len; +} + +static struct proto_ops algif_rng_ops = { + .family = PF_ALG, + + .connect = sock_no_connect, + .socketpair = sock_no_socketpair, + .getname = sock_no_getname, + .ioctl = sock_no_ioctl, + .listen = sock_no_listen, + .shutdown = sock_no_shutdown, + .getsockopt = sock_no_getsockopt, + .mmap = sock_no_mmap, + .bind = sock_no_bind, + .accept = sock_no_accept, + .setsockopt = sock_no_setsockopt, + .poll = sock_no_poll, + .sendmsg = sock_no_sendmsg, + .sendpage = sock_no_sendpage, + + .release = af_alg_release, + .recvmsg = rng_recvmsg, +}; + +static void *rng_bind(const char *name, u32 type, u32 mask) +{ + return crypto_alloc_rng(name, type, mask); +} + +static void rng_release(void *private) +{ + crypto_free_rng(private); +} + +static void rng_sock_destruct(struct sock *sk) +{ + struct alg_sock *ask = alg_sk(sk); + struct rng_ctx *ctx = ask->private; + + sock_kfree_s(sk, ctx, ctx->len); + af_alg_release_parent(sk); +} + +static int rng_accept_parent(void *private, struct sock *sk) +{ + struct rng_ctx *ctx; + struct alg_sock *ask = alg_sk(sk); + unsigned int len = sizeof(*ctx); + + ctx = sock_kmalloc(sk, len, GFP_KERNEL); + if (!ctx) + return -ENOMEM; + + ctx->len = len; + + /* + * No seeding done at that point -- if multiple accepts are + * done on one RNG instance, each resulting FD points to the same + * state of the RNG. + */ + + ctx->drng = private; + ask->private = ctx; + sk->sk_destruct = rng_sock_destruct; + + return 0; +} + +static int rng_setkey(void *private, const u8 *seed, unsigned int seedlen) +{ + /* + * Check whether seedlen is of sufficient size is done in RNG + * implementations. + */ + return crypto_rng_reset(private, (u8 *)seed, seedlen); +} + +static const struct af_alg_type algif_type_rng = { + .bind = rng_bind, + .release = rng_release, + .accept = rng_accept_parent, + .setkey = rng_setkey, + .ops = &algif_rng_ops, + .name = "rng", + .owner = THIS_MODULE +}; + +static int __init rng_init(void) +{ + return af_alg_register_type(&algif_type_rng); +} + +void __exit rng_exit(void) +{ + int err = af_alg_unregister_type(&algif_type_rng); + BUG_ON(err); +} + +module_init(rng_init); +module_exit(rng_exit); |