1 files changed, 342 insertions, 0 deletions
diff --git a/crypto/algif_rng.c b/crypto/algif_rng.c
new file mode 100644
index 000000000..407408c43
--- /dev/null
+++ b/crypto/algif_rng.c
@@ -0,0 +1,342 @@
+/*
+ * 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/capability.h>
+#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;
+	u8 *addtl;
+	size_t addtl_len;
+};
+
+struct rng_parent_ctx {
+	struct crypto_rng *drng;
+	u8 *entropy;
+};
+
+static void rng_reset_addtl(struct rng_ctx *ctx)
+{
+	kfree_sensitive(ctx->addtl);
+	ctx->addtl = NULL;
+	ctx->addtl_len = 0;
+}
+
+static int _rng_recvmsg(struct crypto_rng *drng, struct msghdr *msg, size_t len,
+			u8 *addtl, size_t addtl_len)
+{
+	int err = 0;
+	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_generate(drng, addtl, addtl_len, result, len);
+	if (genlen < 0)
+		return genlen;
+
+	err = memcpy_to_msg(msg, result, len);
+	memzero_explicit(result, len);
+
+	return err ? err : len;
+}
+
+static int rng_recvmsg(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;
+
+	return _rng_recvmsg(ctx->drng, msg, len, NULL, 0);
+}
+
+static int rng_test_recvmsg(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 ret;
+
+	lock_sock(sock->sk);
+	ret = _rng_recvmsg(ctx->drng, msg, len, ctx->addtl, ctx->addtl_len);
+	rng_reset_addtl(ctx);
+	release_sock(sock->sk);
+
+	return ret;
+}
+
+static int rng_test_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
+{
+	int err;
+	struct alg_sock *ask = alg_sk(sock->sk);
+	struct rng_ctx *ctx = ask->private;
+
+	lock_sock(sock->sk);
+	if (len > MAXSIZE) {
+		err = -EMSGSIZE;
+		goto unlock;
+	}
+
+	rng_reset_addtl(ctx);
+	ctx->addtl = kmalloc(len, GFP_KERNEL);
+	if (!ctx->addtl) {
+		err = -ENOMEM;
+		goto unlock;
+	}
+
+	err = memcpy_from_msg(ctx->addtl, msg, len);
+	if (err) {
+		rng_reset_addtl(ctx);
+		goto unlock;
+	}
+	ctx->addtl_len = len;
+
+unlock:
+	release_sock(sock->sk);
+	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,
+	.mmap		=	sock_no_mmap,
+	.bind		=	sock_no_bind,
+	.accept		=	sock_no_accept,
+	.sendmsg	=	sock_no_sendmsg,
+	.sendpage	=	sock_no_sendpage,
+
+	.release	=	af_alg_release,
+	.recvmsg	=	rng_recvmsg,
+};
+
+static struct proto_ops __maybe_unused algif_rng_test_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,
+	.mmap		=	sock_no_mmap,
+	.bind		=	sock_no_bind,
+	.accept		=	sock_no_accept,
+	.sendpage	=	sock_no_sendpage,
+
+	.release	=	af_alg_release,
+	.recvmsg	=	rng_test_recvmsg,
+	.sendmsg	=	rng_test_sendmsg,
+};
+
+static void *rng_bind(const char *name, u32 type, u32 mask)
+{
+	struct rng_parent_ctx *pctx;
+	struct crypto_rng *rng;
+
+	pctx = kzalloc(sizeof(*pctx), GFP_KERNEL);
+	if (!pctx)
+		return ERR_PTR(-ENOMEM);
+
+	rng = crypto_alloc_rng(name, type, mask);
+	if (IS_ERR(rng)) {
+		kfree(pctx);
+		return ERR_CAST(rng);
+	}
+
+	pctx->drng = rng;
+	return pctx;
+}
+
+static void rng_release(void *private)
+{
+	struct rng_parent_ctx *pctx = private;
+
+	if (unlikely(!pctx))
+		return;
+	crypto_free_rng(pctx->drng);
+	kfree_sensitive(pctx->entropy);
+	kfree_sensitive(pctx);
+}
+
+static void rng_sock_destruct(struct sock *sk)
+{
+	struct alg_sock *ask = alg_sk(sk);
+	struct rng_ctx *ctx = ask->private;
+
+	rng_reset_addtl(ctx);
+	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 rng_parent_ctx *pctx = private;
+	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;
+	ctx->addtl = NULL;
+	ctx->addtl_len = 0;
+
+	/*
+	 * 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 = pctx->drng;
+	ask->private = ctx;
+	sk->sk_destruct = rng_sock_destruct;
+
+	/*
+	 * Non NULL pctx->entropy means that CAVP test has been initiated on
+	 * this socket, replace proto_ops algif_rng_ops with algif_rng_test_ops.
+	 */
+	if (IS_ENABLED(CONFIG_CRYPTO_USER_API_RNG_CAVP) && pctx->entropy)
+		sk->sk_socket->ops = &algif_rng_test_ops;
+
+	return 0;
+}
+
+static int rng_setkey(void *private, const u8 *seed, unsigned int seedlen)
+{
+	struct rng_parent_ctx *pctx = private;
+	/*
+	 * Check whether seedlen is of sufficient size is done in RNG
+	 * implementations.
+	 */
+	return crypto_rng_reset(pctx->drng, seed, seedlen);
+}
+
+static int __maybe_unused rng_setentropy(void *private, sockptr_t entropy,
+					 unsigned int len)
+{
+	struct rng_parent_ctx *pctx = private;
+	u8 *kentropy = NULL;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (pctx->entropy)
+		return -EINVAL;
+
+	if (len > MAXSIZE)
+		return -EMSGSIZE;
+
+	if (len) {
+		kentropy = memdup_sockptr(entropy, len);
+		if (IS_ERR(kentropy))
+			return PTR_ERR(kentropy);
+	}
+
+	crypto_rng_alg(pctx->drng)->set_ent(pctx->drng, kentropy, len);
+	/*
+	 * Since rng doesn't perform any memory management for the entropy
+	 * buffer, save kentropy pointer to pctx now to free it after use.
+	 */
+	pctx->entropy = kentropy;
+	return 0;
+}
+
+static const struct af_alg_type algif_type_rng = {
+	.bind		=	rng_bind,
+	.release	=	rng_release,
+	.accept		=	rng_accept_parent,
+	.setkey		=	rng_setkey,
+#ifdef CONFIG_CRYPTO_USER_API_RNG_CAVP
+	.setentropy	=	rng_setentropy,
+#endif
+	.ops		=	&algif_rng_ops,
+	.name		=	"rng",
+	.owner		=	THIS_MODULE
+};
+
+static int __init rng_init(void)
+{
+	return af_alg_register_type(&algif_type_rng);
+}
+
+static 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);