crypto/algif_hash.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * algif_hash: User-space interface for hash algorithms
  *
  * This file provides the user-space API for hash algorithms.
  *
  * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
  */

 #include <crypto/hash.h>
 #include <crypto/if_alg.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/net.h>
 #include <net/sock.h>

 struct hash_ctx {
 	struct af_alg_sgl sgl;

 	u8 *result;

 	struct crypto_wait wait;

 	unsigned int len;
 	bool more;

 	struct ahash_request req;
 };

 static int hash_alloc_result(struct sock *sk, struct hash_ctx *ctx)
 {
 	unsigned ds;

 	if (ctx->result)
 		return 0;

 	ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));

 	ctx->result = sock_kmalloc(sk, ds, GFP_KERNEL);
 	if (!ctx->result)
 		return -ENOMEM;

 	memset(ctx->result, 0, ds);

 	return 0;
 }

 static void hash_free_result(struct sock *sk, struct hash_ctx *ctx)
 {
 	unsigned ds;

 	if (!ctx->result)
 		return;

 	ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));

 	sock_kzfree_s(sk, ctx->result, ds);
 	ctx->result = NULL;
 }

 static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
 			size_t ignored)
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct hash_ctx *ctx = ask->private;
 	ssize_t copied = 0;
 	size_t len, max_pages, npages;
 	bool continuing, need_init = false;
 	int err;

 	max_pages = min_t(size_t, ALG_MAX_PAGES,
 			  DIV_ROUND_UP(sk->sk_sndbuf, PAGE_SIZE));

 	lock_sock(sk);
 	continuing = ctx->more;

 	if (!continuing) {
 		/* Discard a previous request that wasn't marked MSG_MORE. */
 		hash_free_result(sk, ctx);
 		if (!msg_data_left(msg))
 			goto done; /* Zero-length; don't start new req */
 		need_init = true;
 	} else if (!msg_data_left(msg)) {
 		/*
 		 * No data - finalise the prev req if MSG_MORE so any error
 		 * comes out here.
 		 */
 		if (!(msg->msg_flags & MSG_MORE)) {
 			err = hash_alloc_result(sk, ctx);
 			if (err)
 				goto unlock_free_result;
 			ahash_request_set_crypt(&ctx->req, NULL,
 						ctx->result, 0);
 			err = crypto_wait_req(crypto_ahash_final(&ctx->req),
 					      &ctx->wait);
 			if (err)
 				goto unlock_free_result;
 		}
 		goto done_more;
 	}

 	while (msg_data_left(msg)) {
 		ctx->sgl.sgt.sgl = ctx->sgl.sgl;
 		ctx->sgl.sgt.nents = 0;
 		ctx->sgl.sgt.orig_nents = 0;

 		err = -EIO;
 		npages = iov_iter_npages(&msg->msg_iter, max_pages);
 		if (npages == 0)
 			goto unlock_free;

 		sg_init_table(ctx->sgl.sgl, npages);

 		ctx->sgl.need_unpin = iov_iter_extract_will_pin(&msg->msg_iter);

 		err = extract_iter_to_sg(&msg->msg_iter, LONG_MAX,
 					 &ctx->sgl.sgt, npages, 0);
 		if (err < 0)
 			goto unlock_free;
 		len = err;
 		sg_mark_end(ctx->sgl.sgt.sgl + ctx->sgl.sgt.nents - 1);

 		if (!msg_data_left(msg)) {
 			err = hash_alloc_result(sk, ctx);
 			if (err)
 				goto unlock_free;
 		}

 		ahash_request_set_crypt(&ctx->req, ctx->sgl.sgt.sgl,
 					ctx->result, len);

 		if (!msg_data_left(msg) && !continuing &&
 		    !(msg->msg_flags & MSG_MORE)) {
 			err = crypto_ahash_digest(&ctx->req);
 		} else {
 			if (need_init) {
 				err = crypto_wait_req(
 					crypto_ahash_init(&ctx->req),
 					&ctx->wait);
 				if (err)
 					goto unlock_free;
 				need_init = false;
 			}

 			if (msg_data_left(msg) || (msg->msg_flags & MSG_MORE))
 				err = crypto_ahash_update(&ctx->req);
 			else
 				err = crypto_ahash_finup(&ctx->req);
 			continuing = true;
 		}

 		err = crypto_wait_req(err, &ctx->wait);
 		if (err)
 			goto unlock_free;

 		copied += len;
 		af_alg_free_sg(&ctx->sgl);
 	}

 done_more:
 	ctx->more = msg->msg_flags & MSG_MORE;
 done:
 	err = 0;
 unlock:
 	release_sock(sk);
 	return copied ?: err;

 unlock_free:
 	af_alg_free_sg(&ctx->sgl);
 unlock_free_result:
 	hash_free_result(sk, ctx);
 	ctx->more = false;
 	goto unlock;
 }

 static int hash_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 hash_ctx *ctx = ask->private;
 	unsigned ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));
 	bool result;
 	int err;

 	if (len > ds)
 		len = ds;
 	else if (len < ds)
 		msg->msg_flags |= MSG_TRUNC;

 	lock_sock(sk);
 	result = ctx->result;
 	err = hash_alloc_result(sk, ctx);
 	if (err)
 		goto unlock;

 	ahash_request_set_crypt(&ctx->req, NULL, ctx->result, 0);

 	if (!result && !ctx->more) {
 		err = crypto_wait_req(crypto_ahash_init(&ctx->req),
 				      &ctx->wait);
 		if (err)
 			goto unlock;
 	}

 	if (!result || ctx->more) {
 		ctx->more = false;
 		err = crypto_wait_req(crypto_ahash_final(&ctx->req),
 				      &ctx->wait);
 		if (err)
 			goto unlock;
 	}

 	err = memcpy_to_msg(msg, ctx->result, len);

 unlock:
 	hash_free_result(sk, ctx);
 	release_sock(sk);

 	return err ?: len;
 }

 static int hash_accept(struct socket *sock, struct socket *newsock,
 		       struct proto_accept_arg *arg)
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct hash_ctx *ctx = ask->private;
 	struct ahash_request *req = &ctx->req;
 	struct crypto_ahash *tfm;
 	struct sock *sk2;
 	struct alg_sock *ask2;
 	struct hash_ctx *ctx2;
 	char *state;
 	bool more;
 	int err;

 	tfm = crypto_ahash_reqtfm(req);
 	state = kmalloc(crypto_ahash_statesize(tfm), GFP_KERNEL);
 	err = -ENOMEM;
 	if (!state)
 		goto out;

 	lock_sock(sk);
 	more = ctx->more;
 	err = more ? crypto_ahash_export(req, state) : 0;
 	release_sock(sk);

 	if (err)
 		goto out_free_state;

 	err = af_alg_accept(ask->parent, newsock, arg);
 	if (err)
 		goto out_free_state;

 	sk2 = newsock->sk;
 	ask2 = alg_sk(sk2);
 	ctx2 = ask2->private;
 	ctx2->more = more;

 	if (!more)
 		goto out_free_state;

 	err = crypto_ahash_import(&ctx2->req, state);
 	if (err) {
 		sock_orphan(sk2);
 		sock_put(sk2);
 	}

 out_free_state:
 	kfree_sensitive(state);

 out:
 	return err;
 }

 static struct proto_ops algif_hash_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,

 	.release	=	af_alg_release,
 	.sendmsg	=	hash_sendmsg,
 	.recvmsg	=	hash_recvmsg,
 	.accept		=	hash_accept,
 };

 static int hash_check_key(struct socket *sock)
 {
 	int err = 0;
 	struct sock *psk;
 	struct alg_sock *pask;
 	struct crypto_ahash *tfm;
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);

 	lock_sock(sk);
 	if (!atomic_read(&ask->nokey_refcnt))
 		goto unlock_child;

 	psk = ask->parent;
 	pask = alg_sk(ask->parent);
 	tfm = pask->private;

 	err = -ENOKEY;
 	lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
 	if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 		goto unlock;

 	atomic_dec(&pask->nokey_refcnt);
 	atomic_set(&ask->nokey_refcnt, 0);

 	err = 0;

 unlock:
 	release_sock(psk);
 unlock_child:
 	release_sock(sk);

 	return err;
 }

 static int hash_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
 			      size_t size)
 {
 	int err;

 	err = hash_check_key(sock);
 	if (err)
 		return err;

 	return hash_sendmsg(sock, msg, size);
 }

 static int hash_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
 			      size_t ignored, int flags)
 {
 	int err;

 	err = hash_check_key(sock);
 	if (err)
 		return err;

 	return hash_recvmsg(sock, msg, ignored, flags);
 }

 static int hash_accept_nokey(struct socket *sock, struct socket *newsock,
 			     struct proto_accept_arg *arg)
 {
 	int err;

 	err = hash_check_key(sock);
 	if (err)
 		return err;

 	return hash_accept(sock, newsock, arg);
 }

 static struct proto_ops algif_hash_ops_nokey = {
 	.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,

 	.release	=	af_alg_release,
 	.sendmsg	=	hash_sendmsg_nokey,
 	.recvmsg	=	hash_recvmsg_nokey,
 	.accept		=	hash_accept_nokey,
 };

 static void *hash_bind(const char *name, u32 type, u32 mask)
 {
 	return crypto_alloc_ahash(name, type, mask);
 }

 static void hash_release(void *private)
 {
 	crypto_free_ahash(private);
 }

 static int hash_setkey(void *private, const u8 *key, unsigned int keylen)
 {
 	return crypto_ahash_setkey(private, key, keylen);
 }

 static void hash_sock_destruct(struct sock *sk)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct hash_ctx *ctx = ask->private;

 	hash_free_result(sk, ctx);
 	sock_kfree_s(sk, ctx, ctx->len);
 	af_alg_release_parent(sk);
 }

 static int hash_accept_parent_nokey(void *private, struct sock *sk)
 {
 	struct crypto_ahash *tfm = private;
 	struct alg_sock *ask = alg_sk(sk);
 	struct hash_ctx *ctx;
 	unsigned int len = sizeof(*ctx) + crypto_ahash_reqsize(tfm);

 	ctx = sock_kmalloc(sk, len, GFP_KERNEL);
 	if (!ctx)
 		return -ENOMEM;

 	ctx->result = NULL;
 	ctx->len = len;
 	ctx->more = false;
 	crypto_init_wait(&ctx->wait);

 	ask->private = ctx;

 	ahash_request_set_tfm(&ctx->req, tfm);
 	ahash_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
 				   crypto_req_done, &ctx->wait);

 	sk->sk_destruct = hash_sock_destruct;

 	return 0;
 }

 static int hash_accept_parent(void *private, struct sock *sk)
 {
 	struct crypto_ahash *tfm = private;

 	if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 		return -ENOKEY;

 	return hash_accept_parent_nokey(private, sk);
 }

 static const struct af_alg_type algif_type_hash = {
 	.bind		=	hash_bind,
 	.release	=	hash_release,
 	.setkey		=	hash_setkey,
 	.accept		=	hash_accept_parent,
 	.accept_nokey	=	hash_accept_parent_nokey,
 	.ops		=	&algif_hash_ops,
 	.ops_nokey	=	&algif_hash_ops_nokey,
 	.name		=	"hash",
 	.owner		=	THIS_MODULE
 };

 static int __init algif_hash_init(void)
 {
 	return af_alg_register_type(&algif_type_hash);
 }

 static void __exit algif_hash_exit(void)
 {
 	int err = af_alg_unregister_type(&algif_type_hash);
 	BUG_ON(err);
 }

 module_init(algif_hash_init);
 module_exit(algif_hash_exit);
 MODULE_DESCRIPTION("Userspace interface for hash algorithms");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* algif_hash: User-space interface for hash algorithms
	*
	* This file provides the user-space API for hash algorithms.
	*
	* Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
	*/

	#include <crypto/hash.h>
	#include <crypto/if_alg.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/net.h>
	#include <net/sock.h>

	struct hash_ctx {
	struct af_alg_sgl sgl;

	u8 *result;

	struct crypto_wait wait;

	unsigned int len;
	bool more;

	struct ahash_request req;
	};

	static int hash_alloc_result(struct sock sk, struct hash_ctx ctx)
	{
	unsigned ds;

	if (ctx->result)
	return 0;

	ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));

	ctx->result = sock_kmalloc(sk, ds, GFP_KERNEL);
	if (!ctx->result)
	return -ENOMEM;

	memset(ctx->result, 0, ds);

	return 0;
	}

	static void hash_free_result(struct sock sk, struct hash_ctx ctx)
	{
	unsigned ds;

	if (!ctx->result)
	return;

	ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));

	sock_kzfree_s(sk, ctx->result, ds);
	ctx->result = NULL;
	}

	static int hash_sendmsg(struct socket sock, struct msghdr msg,
	size_t ignored)
	{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct hash_ctx *ctx = ask->private;
	ssize_t copied = 0;
	size_t len, max_pages, npages;
	bool continuing, need_init = false;
	int err;

	max_pages = min_t(size_t, ALG_MAX_PAGES,
	DIV_ROUND_UP(sk->sk_sndbuf, PAGE_SIZE));

	lock_sock(sk);
	continuing = ctx->more;

	if (!continuing) {
	/* Discard a previous request that wasn't marked MSG_MORE. */
	hash_free_result(sk, ctx);
	if (!msg_data_left(msg))
	goto done; /* Zero-length; don't start new req */
	need_init = true;
	} else if (!msg_data_left(msg)) {
	/*
	* No data - finalise the prev req if MSG_MORE so any error
	* comes out here.
	*/
	if (!(msg->msg_flags & MSG_MORE)) {
	err = hash_alloc_result(sk, ctx);
	if (err)
	goto unlock_free_result;
	ahash_request_set_crypt(&ctx->req, NULL,
	ctx->result, 0);
	err = crypto_wait_req(crypto_ahash_final(&ctx->req),
	&ctx->wait);
	if (err)
	goto unlock_free_result;
	}
	goto done_more;
	}

	while (msg_data_left(msg)) {
	ctx->sgl.sgt.sgl = ctx->sgl.sgl;
	ctx->sgl.sgt.nents = 0;
	ctx->sgl.sgt.orig_nents = 0;

	err = -EIO;
	npages = iov_iter_npages(&msg->msg_iter, max_pages);
	if (npages == 0)
	goto unlock_free;

	sg_init_table(ctx->sgl.sgl, npages);

	ctx->sgl.need_unpin = iov_iter_extract_will_pin(&msg->msg_iter);

	err = extract_iter_to_sg(&msg->msg_iter, LONG_MAX,
	&ctx->sgl.sgt, npages, 0);
	if (err < 0)
	goto unlock_free;
	len = err;
	sg_mark_end(ctx->sgl.sgt.sgl + ctx->sgl.sgt.nents - 1);

	if (!msg_data_left(msg)) {
	err = hash_alloc_result(sk, ctx);
	if (err)
	goto unlock_free;
	}

	ahash_request_set_crypt(&ctx->req, ctx->sgl.sgt.sgl,
	ctx->result, len);

	if (!msg_data_left(msg) && !continuing &&
	!(msg->msg_flags & MSG_MORE)) {
	err = crypto_ahash_digest(&ctx->req);
	} else {
	if (need_init) {
	err = crypto_wait_req(
	crypto_ahash_init(&ctx->req),
	&ctx->wait);
	if (err)
	goto unlock_free;
	need_init = false;
	}

	if (msg_data_left(msg) \|\| (msg->msg_flags & MSG_MORE))
	err = crypto_ahash_update(&ctx->req);
	else
	err = crypto_ahash_finup(&ctx->req);
	continuing = true;
	}

	err = crypto_wait_req(err, &ctx->wait);
	if (err)
	goto unlock_free;

	copied += len;
	af_alg_free_sg(&ctx->sgl);
	}

	done_more:
	ctx->more = msg->msg_flags & MSG_MORE;
	done:
	err = 0;
	unlock:
	release_sock(sk);
	return copied ?: err;

	unlock_free:
	af_alg_free_sg(&ctx->sgl);
	unlock_free_result:
	hash_free_result(sk, ctx);
	ctx->more = false;
	goto unlock;
	}

	static int hash_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 hash_ctx *ctx = ask->private;
	unsigned ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));
	bool result;
	int err;

	if (len > ds)
	len = ds;
	else if (len < ds)
	msg->msg_flags \|= MSG_TRUNC;

	lock_sock(sk);
	result = ctx->result;
	err = hash_alloc_result(sk, ctx);
	if (err)
	goto unlock;

	ahash_request_set_crypt(&ctx->req, NULL, ctx->result, 0);

	if (!result && !ctx->more) {
	err = crypto_wait_req(crypto_ahash_init(&ctx->req),
	&ctx->wait);
	if (err)
	goto unlock;
	}

	if (!result \|\| ctx->more) {
	ctx->more = false;
	err = crypto_wait_req(crypto_ahash_final(&ctx->req),
	&ctx->wait);
	if (err)
	goto unlock;
	}

	err = memcpy_to_msg(msg, ctx->result, len);

	unlock:
	hash_free_result(sk, ctx);
	release_sock(sk);

	return err ?: len;
	}

	static int hash_accept(struct socket sock, struct socket newsock,
	struct proto_accept_arg *arg)
	{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct hash_ctx *ctx = ask->private;
	struct ahash_request *req = &ctx->req;
	struct crypto_ahash *tfm;
	struct sock *sk2;
	struct alg_sock *ask2;
	struct hash_ctx *ctx2;
	char *state;
	bool more;
	int err;

	tfm = crypto_ahash_reqtfm(req);
	state = kmalloc(crypto_ahash_statesize(tfm), GFP_KERNEL);
	err = -ENOMEM;
	if (!state)
	goto out;

	lock_sock(sk);
	more = ctx->more;
	err = more ? crypto_ahash_export(req, state) : 0;
	release_sock(sk);

	if (err)
	goto out_free_state;

	err = af_alg_accept(ask->parent, newsock, arg);
	if (err)
	goto out_free_state;

	sk2 = newsock->sk;
	ask2 = alg_sk(sk2);
	ctx2 = ask2->private;
	ctx2->more = more;

	if (!more)
	goto out_free_state;

	err = crypto_ahash_import(&ctx2->req, state);
	if (err) {
	sock_orphan(sk2);
	sock_put(sk2);
	}

	out_free_state:
	kfree_sensitive(state);

	out:
	return err;
	}

	static struct proto_ops algif_hash_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,

	.release = af_alg_release,
	.sendmsg = hash_sendmsg,
	.recvmsg = hash_recvmsg,
	.accept = hash_accept,
	};

	static int hash_check_key(struct socket *sock)
	{
	int err = 0;
	struct sock *psk;
	struct alg_sock *pask;
	struct crypto_ahash *tfm;
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);

	lock_sock(sk);
	if (!atomic_read(&ask->nokey_refcnt))
	goto unlock_child;

	psk = ask->parent;
	pask = alg_sk(ask->parent);
	tfm = pask->private;

	err = -ENOKEY;
	lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
	if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
	goto unlock;

	atomic_dec(&pask->nokey_refcnt);
	atomic_set(&ask->nokey_refcnt, 0);

	err = 0;

	unlock:
	release_sock(psk);
	unlock_child:
	release_sock(sk);

	return err;
	}

	static int hash_sendmsg_nokey(struct socket sock, struct msghdr msg,
	size_t size)
	{
	int err;

	err = hash_check_key(sock);
	if (err)
	return err;

	return hash_sendmsg(sock, msg, size);
	}

	static int hash_recvmsg_nokey(struct socket sock, struct msghdr msg,
	size_t ignored, int flags)
	{
	int err;

	err = hash_check_key(sock);
	if (err)
	return err;

	return hash_recvmsg(sock, msg, ignored, flags);
	}

	static int hash_accept_nokey(struct socket sock, struct socket newsock,
	struct proto_accept_arg *arg)
	{
	int err;

	err = hash_check_key(sock);
	if (err)
	return err;

	return hash_accept(sock, newsock, arg);
	}

	static struct proto_ops algif_hash_ops_nokey = {
	.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,

	.release = af_alg_release,
	.sendmsg = hash_sendmsg_nokey,
	.recvmsg = hash_recvmsg_nokey,
	.accept = hash_accept_nokey,
	};

	static void hash_bind(const char name, u32 type, u32 mask)
	{
	return crypto_alloc_ahash(name, type, mask);
	}

	static void hash_release(void *private)
	{
	crypto_free_ahash(private);
	}

	static int hash_setkey(void private, const u8 key, unsigned int keylen)
	{
	return crypto_ahash_setkey(private, key, keylen);
	}

	static void hash_sock_destruct(struct sock *sk)
	{
	struct alg_sock *ask = alg_sk(sk);
	struct hash_ctx *ctx = ask->private;

	hash_free_result(sk, ctx);
	sock_kfree_s(sk, ctx, ctx->len);
	af_alg_release_parent(sk);
	}

	static int hash_accept_parent_nokey(void private, struct sock sk)
	{
	struct crypto_ahash *tfm = private;
	struct alg_sock *ask = alg_sk(sk);
	struct hash_ctx *ctx;
	unsigned int len = sizeof(*ctx) + crypto_ahash_reqsize(tfm);

	ctx = sock_kmalloc(sk, len, GFP_KERNEL);
	if (!ctx)
	return -ENOMEM;

	ctx->result = NULL;
	ctx->len = len;
	ctx->more = false;
	crypto_init_wait(&ctx->wait);

	ask->private = ctx;

	ahash_request_set_tfm(&ctx->req, tfm);
	ahash_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
	crypto_req_done, &ctx->wait);

	sk->sk_destruct = hash_sock_destruct;

	return 0;
	}

	static int hash_accept_parent(void private, struct sock sk)
	{
	struct crypto_ahash *tfm = private;

	if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
	return -ENOKEY;

	return hash_accept_parent_nokey(private, sk);
	}

	static const struct af_alg_type algif_type_hash = {
	.bind = hash_bind,
	.release = hash_release,
	.setkey = hash_setkey,
	.accept = hash_accept_parent,
	.accept_nokey = hash_accept_parent_nokey,
	.ops = &algif_hash_ops,
	.ops_nokey = &algif_hash_ops_nokey,
	.name = "hash",
	.owner = THIS_MODULE
	};

	static int __init algif_hash_init(void)
	{
	return af_alg_register_type(&algif_type_hash);
	}

	static void __exit algif_hash_exit(void)
	{
	int err = af_alg_unregister_type(&algif_type_hash);
	BUG_ON(err);
	}

	module_init(algif_hash_init);
	module_exit(algif_hash_exit);
	MODULE_DESCRIPTION("Userspace interface for hash algorithms");
	MODULE_LICENSE("GPL");