/*
   * 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/sched/signal.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_tfm {
  	struct crypto_skcipher *skcipher;
  	bool has_key;
  };

  struct skcipher_ctx {
  	struct list_head tsgl;
  	struct af_alg_sgl rsgl;
  
  	void *iv;
  
  	struct af_alg_completion completion;

  	atomic_t inflight;

  	size_t used;

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

  	struct skcipher_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;

  	atomic_t *inflight;
  	struct skcipher_request 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 skcipher_async_req *sreq = req->data;

  	struct kiocb *iocb = sreq->iocb;

  	atomic_dec(sreq->inflight);

  	skcipher_free_async_sgls(sreq);

  	kzfree(sreq);

  	iocb->ki_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)

  			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, size_t 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++) {

  			size_t plen = min_t(size_t, 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)
  {

  	DEFINE_WAIT_FUNC(wait, woken_wake_function);

  	int err = -ERESTARTSYS;

  	long timeout;

  
  	if (flags & MSG_DONTWAIT)
  		return -EAGAIN;

  	sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);

  	add_wait_queue(sk_sleep(sk), &wait);

  	for (;;) {
  		if (signal_pending(current))
  			break;

  		timeout = MAX_SCHEDULE_TIMEOUT;

  		if (sk_wait_event(sk, &timeout, skcipher_writable(sk), &wait)) {

  			err = 0;
  			break;
  		}
  	}

  	remove_wait_queue(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 (skwq_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)
  {

  	DEFINE_WAIT_FUNC(wait, woken_wake_function);

  	struct alg_sock *ask = alg_sk(sk);
  	struct skcipher_ctx *ctx = ask->private;
  	long timeout;

  	int err = -ERESTARTSYS;
  
  	if (flags & MSG_DONTWAIT) {
  		return -EAGAIN;
  	}

  	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);

  	add_wait_queue(sk_sleep(sk), &wait);

  	for (;;) {
  		if (signal_pending(current))
  			break;

  		timeout = MAX_SCHEDULE_TIMEOUT;

  		if (sk_wait_event(sk, &timeout, ctx->used, &wait)) {

  			err = 0;
  			break;
  		}
  	}

  	remove_wait_queue(sk_sleep(sk), &wait);

  	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);

  
  	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 (skwq_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 sock *psk = ask->parent;
  	struct alg_sock *pask = alg_sk(psk);

  	struct skcipher_ctx *ctx = ask->private;

  	struct skcipher_tfm *skc = pask->private;
  	struct crypto_skcipher *tfm = skc->skcipher;

  	unsigned ivsize = crypto_skcipher_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;

  		size_t 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;

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

  		do {
  			i = sgl->cur;

  			plen = min_t(size_t, 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 sock *psk = ask->parent;
  	struct alg_sock *pask = alg_sk(psk);

  	struct skcipher_ctx *ctx = ask->private;

  	struct skcipher_tfm *skc = pask->private;
  	struct crypto_skcipher *tfm = skc->skcipher;

  	struct skcipher_sg_list *sgl;
  	struct scatterlist *sg;
  	struct skcipher_async_req *sreq;

  	struct skcipher_request *req;

  	struct skcipher_async_rsgl *last_rsgl = NULL;

  	unsigned int txbufs = 0, len = 0, tx_nents;

  	unsigned int reqsize = crypto_skcipher_reqsize(tfm);
  	unsigned int ivsize = crypto_skcipher_ivsize(tfm);

  	int err = -ENOMEM;

  	bool mark = false;

  	char *iv;

  	sreq = kzalloc(sizeof(*sreq) + reqsize + ivsize, GFP_KERNEL);
  	if (unlikely(!sreq))
  		goto out;

  	req = &sreq->req;
  	iv = (char *)(req + 1) + reqsize;

  	sreq->iocb = msg->msg_iocb;

  	INIT_LIST_HEAD(&sreq->list);

  	sreq->inflight = &ctx->inflight;
  
  	lock_sock(sk);

  	tx_nents = skcipher_all_sg_nents(ctx);

  	sreq->tsg = kcalloc(tx_nents, sizeof(*sg), GFP_KERNEL);

  	if (unlikely(!sreq->tsg))

  		goto unlock;

  	sg_init_table(sreq->tsg, tx_nents);

  	memcpy(iv, ctx->iv, ivsize);
  	skcipher_request_set_tfm(req, tfm);

  	skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,

  				      skcipher_async_cb, sreq);

  
  	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) {
  				err = -ENOMEM;

  				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);

  	skcipher_request_set_crypt(req, sreq->tsg, sreq->first_sgl.sgl.sg,

  				   len, iv);

  	err = ctx->enc ? crypto_skcipher_encrypt(req) :
  			 crypto_skcipher_decrypt(req);

  	if (err == -EINPROGRESS) {
  		atomic_inc(&ctx->inflight);
  		err = -EIOCBQUEUED;

  		sreq = NULL;

  		goto unlock;
  	}
  free:
  	skcipher_free_async_sgls(sreq);

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

  	kzfree(sreq);
  out:

  	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 sock *psk = ask->parent;
  	struct alg_sock *pask = alg_sk(psk);

  	struct skcipher_ctx *ctx = ask->private;

  	struct skcipher_tfm *skc = pask->private;
  	struct crypto_skcipher *tfm = skc->skcipher;
  	unsigned bs = crypto_skcipher_blocksize(tfm);

  	struct skcipher_sg_list *sgl;
  	struct scatterlist *sg;

  	int err = -EAGAIN;
  	int used;
  	long copied = 0;
  
  	lock_sock(sk);

  	while (msg_data_left(msg)) {

  		if (!ctx->used) {

  			err = skcipher_wait_for_data(sk, flags);
  			if (err)

  				goto unlock;

  		}

  		used = min_t(unsigned long, ctx->used, msg_data_left(msg));

  
  		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;

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

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

  		err = af_alg_wait_for_completion(

  				ctx->enc ?

  					crypto_skcipher_encrypt(&ctx->req) :
  					crypto_skcipher_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 int skcipher_check_key(struct socket *sock)
  {

  	int err = 0;

  	struct sock *psk;
  	struct alg_sock *pask;
  	struct skcipher_tfm *tfm;
  	struct sock *sk = sock->sk;
  	struct alg_sock *ask = alg_sk(sk);

  	lock_sock(sk);

  	if (ask->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 (!tfm->has_key)
  		goto unlock;
  
  	if (!pask->refcnt++)
  		sock_hold(psk);
  
  	ask->refcnt = 1;
  	sock_put(psk);
  
  	err = 0;
  
  unlock:
  	release_sock(psk);

  unlock_child:
  	release_sock(sk);

  
  	return err;
  }
  
  static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
  				  size_t size)
  {
  	int err;
  
  	err = skcipher_check_key(sock);
  	if (err)
  		return err;
  
  	return skcipher_sendmsg(sock, msg, size);
  }
  
  static ssize_t skcipher_sendpage_nokey(struct socket *sock, struct page *page,
  				       int offset, size_t size, int flags)
  {
  	int err;
  
  	err = skcipher_check_key(sock);
  	if (err)
  		return err;
  
  	return skcipher_sendpage(sock, page, offset, size, flags);
  }
  
  static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
  				  size_t ignored, int flags)
  {
  	int err;
  
  	err = skcipher_check_key(sock);
  	if (err)
  		return err;
  
  	return skcipher_recvmsg(sock, msg, ignored, flags);
  }
  
  static struct proto_ops algif_skcipher_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,
  	.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_nokey,
  	.sendpage	=	skcipher_sendpage_nokey,
  	.recvmsg	=	skcipher_recvmsg_nokey,
  	.poll		=	skcipher_poll,
  };

  static void *skcipher_bind(const char *name, u32 type, u32 mask)
  {

  	struct skcipher_tfm *tfm;
  	struct crypto_skcipher *skcipher;
  
  	tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
  	if (!tfm)
  		return ERR_PTR(-ENOMEM);
  
  	skcipher = crypto_alloc_skcipher(name, type, mask);
  	if (IS_ERR(skcipher)) {
  		kfree(tfm);
  		return ERR_CAST(skcipher);
  	}
  
  	tfm->skcipher = skcipher;
  
  	return tfm;

  }
  
  static void skcipher_release(void *private)
  {

  	struct skcipher_tfm *tfm = private;
  
  	crypto_free_skcipher(tfm->skcipher);
  	kfree(tfm);

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

  	struct skcipher_tfm *tfm = private;
  	int err;
  
  	err = crypto_skcipher_setkey(tfm->skcipher, key, keylen);
  	tfm->has_key = !err;
  
  	return err;

  }

  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_skcipher *tfm = crypto_skcipher_reqtfm(&ctx->req);

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

  	skcipher_free_sgl(sk);

  	sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));

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

  static int skcipher_accept_parent_nokey(void *private, struct sock *sk)

  {
  	struct skcipher_ctx *ctx;
  	struct alg_sock *ask = alg_sk(sk);

  	struct skcipher_tfm *tfm = private;
  	struct crypto_skcipher *skcipher = tfm->skcipher;
  	unsigned int len = sizeof(*ctx) + crypto_skcipher_reqsize(skcipher);

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

  	ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(skcipher),

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

  	memset(ctx->iv, 0, crypto_skcipher_ivsize(skcipher));

  
  	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;

  	skcipher_request_set_tfm(&ctx->req, skcipher);

  	skcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_SLEEP |
  						 CRYPTO_TFM_REQ_MAY_BACKLOG,

  				      af_alg_complete, &ctx->completion);

  
  	sk->sk_destruct = skcipher_sock_destruct;
  
  	return 0;
  }

  static int skcipher_accept_parent(void *private, struct sock *sk)
  {
  	struct skcipher_tfm *tfm = private;

  	if (!tfm->has_key && crypto_skcipher_has_setkey(tfm->skcipher))

  		return -ENOKEY;

  	return skcipher_accept_parent_nokey(private, sk);

  }

  static const struct af_alg_type algif_type_skcipher = {
  	.bind		=	skcipher_bind,
  	.release	=	skcipher_release,
  	.setkey		=	skcipher_setkey,
  	.accept		=	skcipher_accept_parent,

  	.accept_nokey	=	skcipher_accept_parent_nokey,

  	.ops		=	&algif_skcipher_ops,

  	.ops_nokey	=	&algif_skcipher_ops_nokey,

  	.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");