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);