crypto/algif_skcipher.c - kernel/msm-4.9 - Gitiles

 /*
  * algif_skcipher: User-space interface for skcipher algorithms
  *
  * This file provides the user-space API for symmetric key ciphers.
  *
  * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the Free
  * Software Foundation; either version 2 of the License, or (at your option)
  * any later version.
  *
  */

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

 struct skcipher_sg_list {
 	struct list_head list;

 	int cur;

 	struct scatterlist sg[0];
 };

 struct skcipher_ctx {
 	struct list_head tsgl;
 	struct af_alg_sgl rsgl;

 	void *iv;

 	struct af_alg_completion completion;

 	atomic_t inflight;
 	unsigned used;

 	unsigned int len;
 	bool more;
 	bool merge;
 	bool enc;

 	struct ablkcipher_request req;
 };

 struct skcipher_async_rsgl {
 	struct af_alg_sgl sgl;
 	struct list_head list;
 };

 struct skcipher_async_req {
 	struct kiocb *iocb;
 	struct skcipher_async_rsgl first_sgl;
 	struct list_head list;
 	struct scatterlist *tsg;
 	char iv[];
 };

 #define GET_SREQ(areq, ctx) (struct skcipher_async_req *)((char *)areq + \
 	crypto_ablkcipher_reqsize(crypto_ablkcipher_reqtfm(&ctx->req)))

 #define GET_REQ_SIZE(ctx) \
 	crypto_ablkcipher_reqsize(crypto_ablkcipher_reqtfm(&ctx->req))

 #define GET_IV_SIZE(ctx) \
 	crypto_ablkcipher_ivsize(crypto_ablkcipher_reqtfm(&ctx->req))

 #define MAX_SGL_ENTS ((4096 - sizeof(struct skcipher_sg_list)) / \
 		      sizeof(struct scatterlist) - 1)

 static void skcipher_free_async_sgls(struct skcipher_async_req *sreq)
 {
 	struct skcipher_async_rsgl *rsgl, *tmp;
 	struct scatterlist *sgl;
 	struct scatterlist *sg;
 	int i, n;

 	list_for_each_entry_safe(rsgl, tmp, &sreq->list, list) {
 		af_alg_free_sg(&rsgl->sgl);
 		if (rsgl != &sreq->first_sgl)
 			kfree(rsgl);
 	}
 	sgl = sreq->tsg;
 	n = sg_nents(sgl);
 	for_each_sg(sgl, sg, n, i)
 		put_page(sg_page(sg));

 	kfree(sreq->tsg);
 }

 static void skcipher_async_cb(struct crypto_async_request *req, int err)
 {
 	struct sock *sk = req->data;
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	struct skcipher_async_req *sreq = GET_SREQ(req, ctx);
 	struct kiocb *iocb = sreq->iocb;

 	atomic_dec(&ctx->inflight);
 	skcipher_free_async_sgls(sreq);
 	kfree(req);
 	aio_complete(iocb, err, err);
 }

 static inline int skcipher_sndbuf(struct sock *sk)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;

 	return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
 			  ctx->used, 0);
 }

 static inline bool skcipher_writable(struct sock *sk)
 {
 	return PAGE_SIZE <= skcipher_sndbuf(sk);
 }

 static int skcipher_alloc_sgl(struct sock *sk)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	struct skcipher_sg_list *sgl;
 	struct scatterlist *sg = NULL;

 	sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
 	if (!list_empty(&ctx->tsgl))
 		sg = sgl->sg;

 	if (!sg || sgl->cur >= MAX_SGL_ENTS) {
 		sgl = sock_kmalloc(sk, sizeof(*sgl) +
 				       sizeof(sgl->sg[0]) * (MAX_SGL_ENTS + 1),
 				   GFP_KERNEL);
 		if (!sgl)
 			return -ENOMEM;

 		sg_init_table(sgl->sg, MAX_SGL_ENTS + 1);
 		sgl->cur = 0;

 		if (sg)
 			scatterwalk_sg_chain(sg, MAX_SGL_ENTS + 1, sgl->sg);

 		list_add_tail(&sgl->list, &ctx->tsgl);
 	}

 	return 0;
 }

 static void skcipher_pull_sgl(struct sock *sk, int used, int put)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	struct skcipher_sg_list *sgl;
 	struct scatterlist *sg;
 	int i;

 	while (!list_empty(&ctx->tsgl)) {
 		sgl = list_first_entry(&ctx->tsgl, struct skcipher_sg_list,
 				       list);
 		sg = sgl->sg;

 		for (i = 0; i < sgl->cur; i++) {
 			int plen = min_t(int, used, sg[i].length);

 			if (!sg_page(sg + i))
 				continue;

 			sg[i].length -= plen;
 			sg[i].offset += plen;

 			used -= plen;
 			ctx->used -= plen;

 			if (sg[i].length)
 				return;
 			if (put)
 				put_page(sg_page(sg + i));
 			sg_assign_page(sg + i, NULL);
 		}

 		list_del(&sgl->list);
 		sock_kfree_s(sk, sgl,
 			     sizeof(*sgl) + sizeof(sgl->sg[0]) *
 					    (MAX_SGL_ENTS + 1));
 	}

 	if (!ctx->used)
 		ctx->merge = 0;
 }

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

 	skcipher_pull_sgl(sk, ctx->used, 1);
 }

 static int skcipher_wait_for_wmem(struct sock *sk, unsigned flags)
 {
 	long timeout;
 	DEFINE_WAIT(wait);
 	int err = -ERESTARTSYS;

 	if (flags & MSG_DONTWAIT)
 		return -EAGAIN;

 	set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);

 	for (;;) {
 		if (signal_pending(current))
 			break;
 		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
 		timeout = MAX_SCHEDULE_TIMEOUT;
 		if (sk_wait_event(sk, &timeout, skcipher_writable(sk))) {
 			err = 0;
 			break;
 		}
 	}
 	finish_wait(sk_sleep(sk), &wait);

 	return err;
 }

 static void skcipher_wmem_wakeup(struct sock *sk)
 {
 	struct socket_wq *wq;

 	if (!skcipher_writable(sk))
 		return;

 	rcu_read_lock();
 	wq = rcu_dereference(sk->sk_wq);
 	if (wq_has_sleeper(wq))
 		wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
 							   POLLRDNORM |
 							   POLLRDBAND);
 	sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
 	rcu_read_unlock();
 }

 static int skcipher_wait_for_data(struct sock *sk, unsigned flags)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	long timeout;
 	DEFINE_WAIT(wait);
 	int err = -ERESTARTSYS;

 	if (flags & MSG_DONTWAIT) {
 		return -EAGAIN;
 	}

 	set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);

 	for (;;) {
 		if (signal_pending(current))
 			break;
 		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
 		timeout = MAX_SCHEDULE_TIMEOUT;
 		if (sk_wait_event(sk, &timeout, ctx->used)) {
 			err = 0;
 			break;
 		}
 	}
 	finish_wait(sk_sleep(sk), &wait);

 	clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);

 	return err;
 }

 static void skcipher_data_wakeup(struct sock *sk)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	struct socket_wq *wq;

 	if (!ctx->used)
 		return;

 	rcu_read_lock();
 	wq = rcu_dereference(sk->sk_wq);
 	if (wq_has_sleeper(wq))
 		wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
 							   POLLRDNORM |
 							   POLLRDBAND);
 	sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
 	rcu_read_unlock();
 }

 static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg,
 			    size_t size)
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(&ctx->req);
 	unsigned ivsize = crypto_ablkcipher_ivsize(tfm);
 	struct skcipher_sg_list *sgl;
 	struct af_alg_control con = {};
 	long copied = 0;
 	bool enc = 0;
 	bool init = 0;
 	int err;
 	int i;

 	if (msg->msg_controllen) {
 		err = af_alg_cmsg_send(msg, &con);
 		if (err)
 			return err;

 		init = 1;
 		switch (con.op) {
 		case ALG_OP_ENCRYPT:
 			enc = 1;
 			break;
 		case ALG_OP_DECRYPT:
 			enc = 0;
 			break;
 		default:
 			return -EINVAL;
 		}

 		if (con.iv && con.iv->ivlen != ivsize)
 			return -EINVAL;
 	}

 	err = -EINVAL;

 	lock_sock(sk);
 	if (!ctx->more && ctx->used)
 		goto unlock;

 	if (init) {
 		ctx->enc = enc;
 		if (con.iv)
 			memcpy(ctx->iv, con.iv->iv, ivsize);
 	}

 	while (size) {
 		struct scatterlist *sg;
 		unsigned long len = size;
 		int plen;

 		if (ctx->merge) {
 			sgl = list_entry(ctx->tsgl.prev,
 					 struct skcipher_sg_list, list);
 			sg = sgl->sg + sgl->cur - 1;
 			len = min_t(unsigned long, len,
 				    PAGE_SIZE - sg->offset - sg->length);

 			err = memcpy_from_msg(page_address(sg_page(sg)) +
 					      sg->offset + sg->length,
 					      msg, len);
 			if (err)
 				goto unlock;

 			sg->length += len;
 			ctx->merge = (sg->offset + sg->length) &
 				     (PAGE_SIZE - 1);

 			ctx->used += len;
 			copied += len;
 			size -= len;
 			continue;
 		}

 		if (!skcipher_writable(sk)) {
 			err = skcipher_wait_for_wmem(sk, msg->msg_flags);
 			if (err)
 				goto unlock;
 		}

 		len = min_t(unsigned long, len, skcipher_sndbuf(sk));

 		err = skcipher_alloc_sgl(sk);
 		if (err)
 			goto unlock;

 		sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
 		sg = sgl->sg;
 		sg_unmark_end(sg + sgl->cur);
 		do {
 			i = sgl->cur;
 			plen = min_t(int, len, PAGE_SIZE);

 			sg_assign_page(sg + i, alloc_page(GFP_KERNEL));
 			err = -ENOMEM;
 			if (!sg_page(sg + i))
 				goto unlock;

 			err = memcpy_from_msg(page_address(sg_page(sg + i)),
 					      msg, plen);
 			if (err) {
 				__free_page(sg_page(sg + i));
 				sg_assign_page(sg + i, NULL);
 				goto unlock;
 			}

 			sg[i].length = plen;
 			len -= plen;
 			ctx->used += plen;
 			copied += plen;
 			size -= plen;
 			sgl->cur++;
 		} while (len && sgl->cur < MAX_SGL_ENTS);

 		if (!size)
 			sg_mark_end(sg + sgl->cur - 1);

 		ctx->merge = plen & (PAGE_SIZE - 1);
 	}

 	err = 0;

 	ctx->more = msg->msg_flags & MSG_MORE;

 unlock:
 	skcipher_data_wakeup(sk);
 	release_sock(sk);

 	return copied ?: err;
 }

 static ssize_t skcipher_sendpage(struct socket *sock, struct page *page,
 				 int offset, size_t size, int flags)
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	struct skcipher_sg_list *sgl;
 	int err = -EINVAL;

 	if (flags & MSG_SENDPAGE_NOTLAST)
 		flags |= MSG_MORE;

 	lock_sock(sk);
 	if (!ctx->more && ctx->used)
 		goto unlock;

 	if (!size)
 		goto done;

 	if (!skcipher_writable(sk)) {
 		err = skcipher_wait_for_wmem(sk, flags);
 		if (err)
 			goto unlock;
 	}

 	err = skcipher_alloc_sgl(sk);
 	if (err)
 		goto unlock;

 	ctx->merge = 0;
 	sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);

 	if (sgl->cur)
 		sg_unmark_end(sgl->sg + sgl->cur - 1);

 	sg_mark_end(sgl->sg + sgl->cur);
 	get_page(page);
 	sg_set_page(sgl->sg + sgl->cur, page, size, offset);
 	sgl->cur++;
 	ctx->used += size;

 done:
 	ctx->more = flags & MSG_MORE;

 unlock:
 	skcipher_data_wakeup(sk);
 	release_sock(sk);

 	return err ?: size;
 }

 static int skcipher_all_sg_nents(struct skcipher_ctx *ctx)
 {
 	struct skcipher_sg_list *sgl;
 	struct scatterlist *sg;
 	int nents = 0;

 	list_for_each_entry(sgl, &ctx->tsgl, list) {
 		sg = sgl->sg;

 		while (!sg->length)
 			sg++;

 		nents += sg_nents(sg);
 	}
 	return nents;
 }

 static int skcipher_recvmsg_async(struct socket *sock, struct msghdr *msg,
 				  int flags)
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	struct skcipher_sg_list *sgl;
 	struct scatterlist *sg;
 	struct skcipher_async_req *sreq;
 	struct ablkcipher_request *req;
 	struct skcipher_async_rsgl *last_rsgl = NULL;
 	unsigned int txbufs = 0, len = 0, tx_nents = skcipher_all_sg_nents(ctx);
 	unsigned int reqlen = sizeof(struct skcipher_async_req) +
 				GET_REQ_SIZE(ctx) + GET_IV_SIZE(ctx);
 	int err = -ENOMEM;
 	bool mark = false;

 	lock_sock(sk);
 	req = kmalloc(reqlen, GFP_KERNEL);
 	if (unlikely(!req))
 		goto unlock;

 	sreq = GET_SREQ(req, ctx);
 	sreq->iocb = msg->msg_iocb;
 	memset(&sreq->first_sgl, '\0', sizeof(struct skcipher_async_rsgl));
 	INIT_LIST_HEAD(&sreq->list);
 	sreq->tsg = kcalloc(tx_nents, sizeof(*sg), GFP_KERNEL);
 	if (unlikely(!sreq->tsg)) {
 		kfree(req);
 		goto unlock;
 	}
 	sg_init_table(sreq->tsg, tx_nents);
 	memcpy(sreq->iv, ctx->iv, GET_IV_SIZE(ctx));
 	ablkcipher_request_set_tfm(req, crypto_ablkcipher_reqtfm(&ctx->req));
 	ablkcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
 					skcipher_async_cb, sk);

 	while (iov_iter_count(&msg->msg_iter)) {
 		struct skcipher_async_rsgl *rsgl;
 		int used;

 		if (!ctx->used) {
 			err = skcipher_wait_for_data(sk, flags);
 			if (err)
 				goto free;
 		}
 		sgl = list_first_entry(&ctx->tsgl,
 				       struct skcipher_sg_list, list);
 		sg = sgl->sg;

 		while (!sg->length)
 			sg++;

 		used = min_t(unsigned long, ctx->used,
 			     iov_iter_count(&msg->msg_iter));
 		used = min_t(unsigned long, used, sg->length);

 		if (txbufs == tx_nents) {
 			struct scatterlist *tmp;
 			int x;
 			/* Ran out of tx slots in async request
 			 * need to expand */
 			tmp = kcalloc(tx_nents * 2, sizeof(*tmp),
 				      GFP_KERNEL);
 			if (!tmp)
 				goto free;

 			sg_init_table(tmp, tx_nents * 2);
 			for (x = 0; x < tx_nents; x++)
 				sg_set_page(&tmp[x], sg_page(&sreq->tsg[x]),
 					    sreq->tsg[x].length,
 					    sreq->tsg[x].offset);
 			kfree(sreq->tsg);
 			sreq->tsg = tmp;
 			tx_nents *= 2;
 			mark = true;
 		}
 		/* Need to take over the tx sgl from ctx
 		 * to the asynch req - these sgls will be freed later */
 		sg_set_page(sreq->tsg + txbufs++, sg_page(sg), sg->length,
 			    sg->offset);

 		if (list_empty(&sreq->list)) {
 			rsgl = &sreq->first_sgl;
 			list_add_tail(&rsgl->list, &sreq->list);
 		} else {
 			rsgl = kmalloc(sizeof(*rsgl), GFP_KERNEL);
 			if (!rsgl) {
 				err = -ENOMEM;
 				goto free;
 			}
 			list_add_tail(&rsgl->list, &sreq->list);
 		}

 		used = af_alg_make_sg(&rsgl->sgl, &msg->msg_iter, used);
 		err = used;
 		if (used < 0)
 			goto free;
 		if (last_rsgl)
 			af_alg_link_sg(&last_rsgl->sgl, &rsgl->sgl);

 		last_rsgl = rsgl;
 		len += used;
 		skcipher_pull_sgl(sk, used, 0);
 		iov_iter_advance(&msg->msg_iter, used);
 	}

 	if (mark)
 		sg_mark_end(sreq->tsg + txbufs - 1);

 	ablkcipher_request_set_crypt(req, sreq->tsg, sreq->first_sgl.sgl.sg,
 				     len, sreq->iv);
 	err = ctx->enc ? crypto_ablkcipher_encrypt(req) :
 			 crypto_ablkcipher_decrypt(req);
 	if (err == -EINPROGRESS) {
 		atomic_inc(&ctx->inflight);
 		err = -EIOCBQUEUED;
 		goto unlock;
 	}
 free:
 	skcipher_free_async_sgls(sreq);
 	kfree(req);
 unlock:
 	skcipher_wmem_wakeup(sk);
 	release_sock(sk);
 	return err;
 }

 static int skcipher_recvmsg_sync(struct socket *sock, struct msghdr *msg,
 				 int flags)
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	unsigned bs = crypto_ablkcipher_blocksize(crypto_ablkcipher_reqtfm(
 		&ctx->req));
 	struct skcipher_sg_list *sgl;
 	struct scatterlist *sg;
 	int err = -EAGAIN;
 	int used;
 	long copied = 0;

 	lock_sock(sk);
 	while (iov_iter_count(&msg->msg_iter)) {
 		sgl = list_first_entry(&ctx->tsgl,
 				       struct skcipher_sg_list, list);
 		sg = sgl->sg;

 		while (!sg->length)
 			sg++;

 		if (!ctx->used) {
 			err = skcipher_wait_for_data(sk, flags);
 			if (err)
 				goto unlock;
 		}

 		used = min_t(unsigned long, ctx->used, iov_iter_count(&msg->msg_iter));

 		used = af_alg_make_sg(&ctx->rsgl, &msg->msg_iter, used);
 		err = used;
 		if (err < 0)
 			goto unlock;

 		if (ctx->more || used < ctx->used)
 			used -= used % bs;

 		err = -EINVAL;
 		if (!used)
 			goto free;

 		ablkcipher_request_set_crypt(&ctx->req, sg,
 					     ctx->rsgl.sg, used,
 					     ctx->iv);

 		err = af_alg_wait_for_completion(
 				ctx->enc ?
 					crypto_ablkcipher_encrypt(&ctx->req) :
 					crypto_ablkcipher_decrypt(&ctx->req),
 				&ctx->completion);

 free:
 		af_alg_free_sg(&ctx->rsgl);

 		if (err)
 			goto unlock;

 		copied += used;
 		skcipher_pull_sgl(sk, used, 1);
 		iov_iter_advance(&msg->msg_iter, used);
 	}

 	err = 0;

 unlock:
 	skcipher_wmem_wakeup(sk);
 	release_sock(sk);

 	return copied ?: err;
 }

 static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 			    size_t ignored, int flags)
 {
 	return (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) ?
 		skcipher_recvmsg_async(sock, msg, flags) :
 		skcipher_recvmsg_sync(sock, msg, flags);
 }

 static unsigned int skcipher_poll(struct file *file, struct socket *sock,
 				  poll_table *wait)
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	unsigned int mask;

 	sock_poll_wait(file, sk_sleep(sk), wait);
 	mask = 0;

 	if (ctx->used)
 		mask |= POLLIN | POLLRDNORM;

 	if (skcipher_writable(sk))
 		mask |= POLLOUT | POLLWRNORM | POLLWRBAND;

 	return mask;
 }

 static struct proto_ops algif_skcipher_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,

 	.release	=	af_alg_release,
 	.sendmsg	=	skcipher_sendmsg,
 	.sendpage	=	skcipher_sendpage,
 	.recvmsg	=	skcipher_recvmsg,
 	.poll		=	skcipher_poll,
 };

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

 static void skcipher_release(void *private)
 {
 	crypto_free_ablkcipher(private);
 }

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

 static void skcipher_wait(struct sock *sk)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	int ctr = 0;

 	while (atomic_read(&ctx->inflight) && ctr++ < 100)
 		msleep(100);
 }

 static void skcipher_sock_destruct(struct sock *sk)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
 	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(&ctx->req);

 	if (atomic_read(&ctx->inflight))
 		skcipher_wait(sk);

 	skcipher_free_sgl(sk);
 	sock_kzfree_s(sk, ctx->iv, crypto_ablkcipher_ivsize(tfm));
 	sock_kfree_s(sk, ctx, ctx->len);
 	af_alg_release_parent(sk);
 }

 static int skcipher_accept_parent(void *private, struct sock *sk)
 {
 	struct skcipher_ctx *ctx;
 	struct alg_sock *ask = alg_sk(sk);
 	unsigned int len = sizeof(*ctx) + crypto_ablkcipher_reqsize(private);

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

 	ctx->iv = sock_kmalloc(sk, crypto_ablkcipher_ivsize(private),
 			       GFP_KERNEL);
 	if (!ctx->iv) {
 		sock_kfree_s(sk, ctx, len);
 		return -ENOMEM;
 	}

 	memset(ctx->iv, 0, crypto_ablkcipher_ivsize(private));

 	INIT_LIST_HEAD(&ctx->tsgl);
 	ctx->len = len;
 	ctx->used = 0;
 	ctx->more = 0;
 	ctx->merge = 0;
 	ctx->enc = 0;
 	atomic_set(&ctx->inflight, 0);
 	af_alg_init_completion(&ctx->completion);

 	ask->private = ctx;

 	ablkcipher_request_set_tfm(&ctx->req, private);
 	ablkcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
 					af_alg_complete, &ctx->completion);

 	sk->sk_destruct = skcipher_sock_destruct;

 	return 0;
 }

 static const struct af_alg_type algif_type_skcipher = {
 	.bind		=	skcipher_bind,
 	.release	=	skcipher_release,
 	.setkey		=	skcipher_setkey,
 	.accept		=	skcipher_accept_parent,
 	.ops		=	&algif_skcipher_ops,
 	.name		=	"skcipher",
 	.owner		=	THIS_MODULE
 };

 static int __init algif_skcipher_init(void)
 {
 	return af_alg_register_type(&algif_type_skcipher);
 }

 static void __exit algif_skcipher_exit(void)
 {
 	int err = af_alg_unregister_type(&algif_type_skcipher);
 	BUG_ON(err);
 }

 module_init(algif_skcipher_init);
 module_exit(algif_skcipher_exit);
 MODULE_LICENSE("GPL");
	/*
	* algif_skcipher: User-space interface for skcipher algorithms
	*
	* This file provides the user-space API for symmetric key ciphers.
	*
	* Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License as published by the Free
	* Software Foundation; either version 2 of the License, or (at your option)
	* any later version.
	*
	*/

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

	struct skcipher_sg_list {
	struct list_head list;

	int cur;

	struct scatterlist sg[0];
	};

	struct skcipher_ctx {
	struct list_head tsgl;
	struct af_alg_sgl rsgl;

	void *iv;

	struct af_alg_completion completion;

	atomic_t inflight;
	unsigned used;

	unsigned int len;
	bool more;
	bool merge;
	bool enc;

	struct ablkcipher_request req;
	};

	struct skcipher_async_rsgl {
	struct af_alg_sgl sgl;
	struct list_head list;
	};

	struct skcipher_async_req {
	struct kiocb *iocb;
	struct skcipher_async_rsgl first_sgl;
	struct list_head list;
	struct scatterlist *tsg;
	char iv[];
	};

	#define GET_SREQ(areq, ctx) (struct skcipher_async_req )((char )areq + \
	crypto_ablkcipher_reqsize(crypto_ablkcipher_reqtfm(&ctx->req)))

	#define GET_REQ_SIZE(ctx) \
	crypto_ablkcipher_reqsize(crypto_ablkcipher_reqtfm(&ctx->req))

	#define GET_IV_SIZE(ctx) \
	crypto_ablkcipher_ivsize(crypto_ablkcipher_reqtfm(&ctx->req))

	#define MAX_SGL_ENTS ((4096 - sizeof(struct skcipher_sg_list)) / \
	sizeof(struct scatterlist) - 1)

	static void skcipher_free_async_sgls(struct skcipher_async_req *sreq)
	{
	struct skcipher_async_rsgl rsgl, tmp;
	struct scatterlist *sgl;
	struct scatterlist *sg;
	int i, n;

	list_for_each_entry_safe(rsgl, tmp, &sreq->list, list) {
	af_alg_free_sg(&rsgl->sgl);
	if (rsgl != &sreq->first_sgl)
	kfree(rsgl);
	}
	sgl = sreq->tsg;
	n = sg_nents(sgl);
	for_each_sg(sgl, sg, n, i)
	put_page(sg_page(sg));

	kfree(sreq->tsg);
	}

	static void skcipher_async_cb(struct crypto_async_request *req, int err)
	{
	struct sock *sk = req->data;
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	struct skcipher_async_req *sreq = GET_SREQ(req, ctx);
	struct kiocb *iocb = sreq->iocb;

	atomic_dec(&ctx->inflight);
	skcipher_free_async_sgls(sreq);
	kfree(req);
	aio_complete(iocb, err, err);
	}

	static inline int skcipher_sndbuf(struct sock *sk)
	{
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;

	return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
	ctx->used, 0);
	}

	static inline bool skcipher_writable(struct sock *sk)
	{
	return PAGE_SIZE <= skcipher_sndbuf(sk);
	}

	static int skcipher_alloc_sgl(struct sock *sk)
	{
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	struct skcipher_sg_list *sgl;
	struct scatterlist *sg = NULL;

	sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
	if (!list_empty(&ctx->tsgl))
	sg = sgl->sg;

	if (!sg \|\| sgl->cur >= MAX_SGL_ENTS) {
	sgl = sock_kmalloc(sk, sizeof(*sgl) +
	sizeof(sgl->sg[0]) * (MAX_SGL_ENTS + 1),
	GFP_KERNEL);
	if (!sgl)
	return -ENOMEM;

	sg_init_table(sgl->sg, MAX_SGL_ENTS + 1);
	sgl->cur = 0;

	if (sg)
	scatterwalk_sg_chain(sg, MAX_SGL_ENTS + 1, sgl->sg);

	list_add_tail(&sgl->list, &ctx->tsgl);
	}

	return 0;
	}

	static void skcipher_pull_sgl(struct sock *sk, int used, int put)
	{
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	struct skcipher_sg_list *sgl;
	struct scatterlist *sg;
	int i;

	while (!list_empty(&ctx->tsgl)) {
	sgl = list_first_entry(&ctx->tsgl, struct skcipher_sg_list,
	list);
	sg = sgl->sg;

	for (i = 0; i < sgl->cur; i++) {
	int plen = min_t(int, used, sg[i].length);

	if (!sg_page(sg + i))
	continue;

	sg[i].length -= plen;
	sg[i].offset += plen;

	used -= plen;
	ctx->used -= plen;

	if (sg[i].length)
	return;
	if (put)
	put_page(sg_page(sg + i));
	sg_assign_page(sg + i, NULL);
	}

	list_del(&sgl->list);
	sock_kfree_s(sk, sgl,
	sizeof(sgl) + sizeof(sgl->sg[0])
	(MAX_SGL_ENTS + 1));
	}

	if (!ctx->used)
	ctx->merge = 0;
	}

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

	skcipher_pull_sgl(sk, ctx->used, 1);
	}

	static int skcipher_wait_for_wmem(struct sock *sk, unsigned flags)
	{
	long timeout;
	DEFINE_WAIT(wait);
	int err = -ERESTARTSYS;

	if (flags & MSG_DONTWAIT)
	return -EAGAIN;

	set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);

	for (;;) {
	if (signal_pending(current))
	break;
	prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
	timeout = MAX_SCHEDULE_TIMEOUT;
	if (sk_wait_event(sk, &timeout, skcipher_writable(sk))) {
	err = 0;
	break;
	}
	}
	finish_wait(sk_sleep(sk), &wait);

	return err;
	}

	static void skcipher_wmem_wakeup(struct sock *sk)
	{
	struct socket_wq *wq;

	if (!skcipher_writable(sk))
	return;

	rcu_read_lock();
	wq = rcu_dereference(sk->sk_wq);
	if (wq_has_sleeper(wq))
	wake_up_interruptible_sync_poll(&wq->wait, POLLIN \|
	POLLRDNORM \|
	POLLRDBAND);
	sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
	rcu_read_unlock();
	}

	static int skcipher_wait_for_data(struct sock *sk, unsigned flags)
	{
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	long timeout;
	DEFINE_WAIT(wait);
	int err = -ERESTARTSYS;

	if (flags & MSG_DONTWAIT) {
	return -EAGAIN;
	}

	set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);

	for (;;) {
	if (signal_pending(current))
	break;
	prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
	timeout = MAX_SCHEDULE_TIMEOUT;
	if (sk_wait_event(sk, &timeout, ctx->used)) {
	err = 0;
	break;
	}
	}
	finish_wait(sk_sleep(sk), &wait);

	clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);

	return err;
	}

	static void skcipher_data_wakeup(struct sock *sk)
	{
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	struct socket_wq *wq;

	if (!ctx->used)
	return;

	rcu_read_lock();
	wq = rcu_dereference(sk->sk_wq);
	if (wq_has_sleeper(wq))
	wake_up_interruptible_sync_poll(&wq->wait, POLLOUT \|
	POLLRDNORM \|
	POLLRDBAND);
	sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
	rcu_read_unlock();
	}

	static int skcipher_sendmsg(struct socket sock, struct msghdr msg,
	size_t size)
	{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(&ctx->req);
	unsigned ivsize = crypto_ablkcipher_ivsize(tfm);
	struct skcipher_sg_list *sgl;
	struct af_alg_control con = {};
	long copied = 0;
	bool enc = 0;
	bool init = 0;
	int err;
	int i;

	if (msg->msg_controllen) {
	err = af_alg_cmsg_send(msg, &con);
	if (err)
	return err;

	init = 1;
	switch (con.op) {
	case ALG_OP_ENCRYPT:
	enc = 1;
	break;
	case ALG_OP_DECRYPT:
	enc = 0;
	break;
	default:
	return -EINVAL;
	}

	if (con.iv && con.iv->ivlen != ivsize)
	return -EINVAL;
	}

	err = -EINVAL;

	lock_sock(sk);
	if (!ctx->more && ctx->used)
	goto unlock;

	if (init) {
	ctx->enc = enc;
	if (con.iv)
	memcpy(ctx->iv, con.iv->iv, ivsize);
	}

	while (size) {
	struct scatterlist *sg;
	unsigned long len = size;
	int plen;

	if (ctx->merge) {
	sgl = list_entry(ctx->tsgl.prev,
	struct skcipher_sg_list, list);
	sg = sgl->sg + sgl->cur - 1;
	len = min_t(unsigned long, len,
	PAGE_SIZE - sg->offset - sg->length);

	err = memcpy_from_msg(page_address(sg_page(sg)) +
	sg->offset + sg->length,
	msg, len);
	if (err)
	goto unlock;

	sg->length += len;
	ctx->merge = (sg->offset + sg->length) &
	(PAGE_SIZE - 1);

	ctx->used += len;
	copied += len;
	size -= len;
	continue;
	}

	if (!skcipher_writable(sk)) {
	err = skcipher_wait_for_wmem(sk, msg->msg_flags);
	if (err)
	goto unlock;
	}

	len = min_t(unsigned long, len, skcipher_sndbuf(sk));

	err = skcipher_alloc_sgl(sk);
	if (err)
	goto unlock;

	sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
	sg = sgl->sg;
	sg_unmark_end(sg + sgl->cur);
	do {
	i = sgl->cur;
	plen = min_t(int, len, PAGE_SIZE);

	sg_assign_page(sg + i, alloc_page(GFP_KERNEL));
	err = -ENOMEM;
	if (!sg_page(sg + i))
	goto unlock;

	err = memcpy_from_msg(page_address(sg_page(sg + i)),
	msg, plen);
	if (err) {
	__free_page(sg_page(sg + i));
	sg_assign_page(sg + i, NULL);
	goto unlock;
	}

	sg[i].length = plen;
	len -= plen;
	ctx->used += plen;
	copied += plen;
	size -= plen;
	sgl->cur++;
	} while (len && sgl->cur < MAX_SGL_ENTS);

	if (!size)
	sg_mark_end(sg + sgl->cur - 1);

	ctx->merge = plen & (PAGE_SIZE - 1);
	}

	err = 0;

	ctx->more = msg->msg_flags & MSG_MORE;

	unlock:
	skcipher_data_wakeup(sk);
	release_sock(sk);

	return copied ?: err;
	}

	static ssize_t skcipher_sendpage(struct socket sock, struct page page,
	int offset, size_t size, int flags)
	{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	struct skcipher_sg_list *sgl;
	int err = -EINVAL;

	if (flags & MSG_SENDPAGE_NOTLAST)
	flags \|= MSG_MORE;

	lock_sock(sk);
	if (!ctx->more && ctx->used)
	goto unlock;

	if (!size)
	goto done;

	if (!skcipher_writable(sk)) {
	err = skcipher_wait_for_wmem(sk, flags);
	if (err)
	goto unlock;
	}

	err = skcipher_alloc_sgl(sk);
	if (err)
	goto unlock;

	ctx->merge = 0;
	sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);

	if (sgl->cur)
	sg_unmark_end(sgl->sg + sgl->cur - 1);

	sg_mark_end(sgl->sg + sgl->cur);
	get_page(page);
	sg_set_page(sgl->sg + sgl->cur, page, size, offset);
	sgl->cur++;
	ctx->used += size;

	done:
	ctx->more = flags & MSG_MORE;

	unlock:
	skcipher_data_wakeup(sk);
	release_sock(sk);

	return err ?: size;
	}

	static int skcipher_all_sg_nents(struct skcipher_ctx *ctx)
	{
	struct skcipher_sg_list *sgl;
	struct scatterlist *sg;
	int nents = 0;

	list_for_each_entry(sgl, &ctx->tsgl, list) {
	sg = sgl->sg;

	while (!sg->length)
	sg++;

	nents += sg_nents(sg);
	}
	return nents;
	}

	static int skcipher_recvmsg_async(struct socket sock, struct msghdr msg,
	int flags)
	{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	struct skcipher_sg_list *sgl;
	struct scatterlist *sg;
	struct skcipher_async_req *sreq;
	struct ablkcipher_request *req;
	struct skcipher_async_rsgl *last_rsgl = NULL;
	unsigned int txbufs = 0, len = 0, tx_nents = skcipher_all_sg_nents(ctx);
	unsigned int reqlen = sizeof(struct skcipher_async_req) +
	GET_REQ_SIZE(ctx) + GET_IV_SIZE(ctx);
	int err = -ENOMEM;
	bool mark = false;

	lock_sock(sk);
	req = kmalloc(reqlen, GFP_KERNEL);
	if (unlikely(!req))
	goto unlock;

	sreq = GET_SREQ(req, ctx);
	sreq->iocb = msg->msg_iocb;
	memset(&sreq->first_sgl, '\0', sizeof(struct skcipher_async_rsgl));
	INIT_LIST_HEAD(&sreq->list);
	sreq->tsg = kcalloc(tx_nents, sizeof(*sg), GFP_KERNEL);
	if (unlikely(!sreq->tsg)) {
	kfree(req);
	goto unlock;
	}
	sg_init_table(sreq->tsg, tx_nents);
	memcpy(sreq->iv, ctx->iv, GET_IV_SIZE(ctx));
	ablkcipher_request_set_tfm(req, crypto_ablkcipher_reqtfm(&ctx->req));
	ablkcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
	skcipher_async_cb, sk);

	while (iov_iter_count(&msg->msg_iter)) {
	struct skcipher_async_rsgl *rsgl;
	int used;

	if (!ctx->used) {
	err = skcipher_wait_for_data(sk, flags);
	if (err)
	goto free;
	}
	sgl = list_first_entry(&ctx->tsgl,
	struct skcipher_sg_list, list);
	sg = sgl->sg;

	while (!sg->length)
	sg++;

	used = min_t(unsigned long, ctx->used,
	iov_iter_count(&msg->msg_iter));
	used = min_t(unsigned long, used, sg->length);

	if (txbufs == tx_nents) {
	struct scatterlist *tmp;
	int x;
	/* Ran out of tx slots in async request
	* need to expand */
	tmp = kcalloc(tx_nents * 2, sizeof(*tmp),
	GFP_KERNEL);
	if (!tmp)
	goto free;

	sg_init_table(tmp, tx_nents * 2);
	for (x = 0; x < tx_nents; x++)
	sg_set_page(&tmp[x], sg_page(&sreq->tsg[x]),
	sreq->tsg[x].length,
	sreq->tsg[x].offset);
	kfree(sreq->tsg);
	sreq->tsg = tmp;
	tx_nents *= 2;
	mark = true;
	}
	/* Need to take over the tx sgl from ctx
	* to the asynch req - these sgls will be freed later */
	sg_set_page(sreq->tsg + txbufs++, sg_page(sg), sg->length,
	sg->offset);

	if (list_empty(&sreq->list)) {
	rsgl = &sreq->first_sgl;
	list_add_tail(&rsgl->list, &sreq->list);
	} else {
	rsgl = kmalloc(sizeof(*rsgl), GFP_KERNEL);
	if (!rsgl) {
	err = -ENOMEM;
	goto free;
	}
	list_add_tail(&rsgl->list, &sreq->list);
	}

	used = af_alg_make_sg(&rsgl->sgl, &msg->msg_iter, used);
	err = used;
	if (used < 0)
	goto free;
	if (last_rsgl)
	af_alg_link_sg(&last_rsgl->sgl, &rsgl->sgl);

	last_rsgl = rsgl;
	len += used;
	skcipher_pull_sgl(sk, used, 0);
	iov_iter_advance(&msg->msg_iter, used);
	}

	if (mark)
	sg_mark_end(sreq->tsg + txbufs - 1);

	ablkcipher_request_set_crypt(req, sreq->tsg, sreq->first_sgl.sgl.sg,
	len, sreq->iv);
	err = ctx->enc ? crypto_ablkcipher_encrypt(req) :
	crypto_ablkcipher_decrypt(req);
	if (err == -EINPROGRESS) {
	atomic_inc(&ctx->inflight);
	err = -EIOCBQUEUED;
	goto unlock;
	}
	free:
	skcipher_free_async_sgls(sreq);
	kfree(req);
	unlock:
	skcipher_wmem_wakeup(sk);
	release_sock(sk);
	return err;
	}

	static int skcipher_recvmsg_sync(struct socket sock, struct msghdr msg,
	int flags)
	{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	unsigned bs = crypto_ablkcipher_blocksize(crypto_ablkcipher_reqtfm(
	&ctx->req));
	struct skcipher_sg_list *sgl;
	struct scatterlist *sg;
	int err = -EAGAIN;
	int used;
	long copied = 0;

	lock_sock(sk);
	while (iov_iter_count(&msg->msg_iter)) {
	sgl = list_first_entry(&ctx->tsgl,
	struct skcipher_sg_list, list);
	sg = sgl->sg;

	while (!sg->length)
	sg++;

	if (!ctx->used) {
	err = skcipher_wait_for_data(sk, flags);
	if (err)
	goto unlock;
	}

	used = min_t(unsigned long, ctx->used, iov_iter_count(&msg->msg_iter));

	used = af_alg_make_sg(&ctx->rsgl, &msg->msg_iter, used);
	err = used;
	if (err < 0)
	goto unlock;

	if (ctx->more \|\| used < ctx->used)
	used -= used % bs;

	err = -EINVAL;
	if (!used)
	goto free;

	ablkcipher_request_set_crypt(&ctx->req, sg,
	ctx->rsgl.sg, used,
	ctx->iv);

	err = af_alg_wait_for_completion(
	ctx->enc ?
	crypto_ablkcipher_encrypt(&ctx->req) :
	crypto_ablkcipher_decrypt(&ctx->req),
	&ctx->completion);

	free:
	af_alg_free_sg(&ctx->rsgl);

	if (err)
	goto unlock;

	copied += used;
	skcipher_pull_sgl(sk, used, 1);
	iov_iter_advance(&msg->msg_iter, used);
	}

	err = 0;

	unlock:
	skcipher_wmem_wakeup(sk);
	release_sock(sk);

	return copied ?: err;
	}

	static int skcipher_recvmsg(struct socket sock, struct msghdr msg,
	size_t ignored, int flags)
	{
	return (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) ?
	skcipher_recvmsg_async(sock, msg, flags) :
	skcipher_recvmsg_sync(sock, msg, flags);
	}

	static unsigned int skcipher_poll(struct file file, struct socket sock,
	poll_table *wait)
	{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	unsigned int mask;

	sock_poll_wait(file, sk_sleep(sk), wait);
	mask = 0;

	if (ctx->used)
	mask \|= POLLIN \| POLLRDNORM;

	if (skcipher_writable(sk))
	mask \|= POLLOUT \| POLLWRNORM \| POLLWRBAND;

	return mask;
	}

	static struct proto_ops algif_skcipher_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,

	.release = af_alg_release,
	.sendmsg = skcipher_sendmsg,
	.sendpage = skcipher_sendpage,
	.recvmsg = skcipher_recvmsg,
	.poll = skcipher_poll,
	};

	static void skcipher_bind(const char name, u32 type, u32 mask)
	{
	return crypto_alloc_ablkcipher(name, type, mask);
	}

	static void skcipher_release(void *private)
	{
	crypto_free_ablkcipher(private);
	}

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

	static void skcipher_wait(struct sock *sk)
	{
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	int ctr = 0;

	while (atomic_read(&ctx->inflight) && ctr++ < 100)
	msleep(100);
	}

	static void skcipher_sock_destruct(struct sock *sk)
	{
	struct alg_sock *ask = alg_sk(sk);
	struct skcipher_ctx *ctx = ask->private;
	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(&ctx->req);

	if (atomic_read(&ctx->inflight))
	skcipher_wait(sk);

	skcipher_free_sgl(sk);
	sock_kzfree_s(sk, ctx->iv, crypto_ablkcipher_ivsize(tfm));
	sock_kfree_s(sk, ctx, ctx->len);
	af_alg_release_parent(sk);
	}

	static int skcipher_accept_parent(void private, struct sock sk)
	{
	struct skcipher_ctx *ctx;
	struct alg_sock *ask = alg_sk(sk);
	unsigned int len = sizeof(*ctx) + crypto_ablkcipher_reqsize(private);

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

	ctx->iv = sock_kmalloc(sk, crypto_ablkcipher_ivsize(private),
	GFP_KERNEL);
	if (!ctx->iv) {
	sock_kfree_s(sk, ctx, len);
	return -ENOMEM;
	}

	memset(ctx->iv, 0, crypto_ablkcipher_ivsize(private));

	INIT_LIST_HEAD(&ctx->tsgl);
	ctx->len = len;
	ctx->used = 0;
	ctx->more = 0;
	ctx->merge = 0;
	ctx->enc = 0;
	atomic_set(&ctx->inflight, 0);
	af_alg_init_completion(&ctx->completion);

	ask->private = ctx;

	ablkcipher_request_set_tfm(&ctx->req, private);
	ablkcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
	af_alg_complete, &ctx->completion);

	sk->sk_destruct = skcipher_sock_destruct;

	return 0;
	}

	static const struct af_alg_type algif_type_skcipher = {
	.bind = skcipher_bind,
	.release = skcipher_release,
	.setkey = skcipher_setkey,
	.accept = skcipher_accept_parent,
	.ops = &algif_skcipher_ops,
	.name = "skcipher",
	.owner = THIS_MODULE
	};

	static int __init algif_skcipher_init(void)
	{
	return af_alg_register_type(&algif_type_skcipher);
	}

	static void __exit algif_skcipher_exit(void)
	{
	int err = af_alg_unregister_type(&algif_type_skcipher);
	BUG_ON(err);
	}

	module_init(algif_skcipher_init);
	module_exit(algif_skcipher_exit);
	MODULE_LICENSE("GPL");