// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * af_alg: User-space algorithm interface
   *
   * This file provides the user-space API for algorithms.
   *
   * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>

   */

  #include <linux/atomic.h>

  #include <crypto/if_alg.h>
  #include <linux/crypto.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/list.h>
  #include <linux/module.h>
  #include <linux/net.h>
  #include <linux/rwsem.h>

  #include <linux/sched.h>

  #include <linux/sched/signal.h>

  #include <linux/security.h>

  
  struct alg_type_list {
  	const struct af_alg_type *type;
  	struct list_head list;
  };

  static atomic_long_t alg_memory_allocated;

  
  static struct proto alg_proto = {
  	.name			= "ALG",
  	.owner			= THIS_MODULE,
  	.memory_allocated	= &alg_memory_allocated,
  	.obj_size		= sizeof(struct alg_sock),
  };
  
  static LIST_HEAD(alg_types);
  static DECLARE_RWSEM(alg_types_sem);
  
  static const struct af_alg_type *alg_get_type(const char *name)
  {
  	const struct af_alg_type *type = ERR_PTR(-ENOENT);
  	struct alg_type_list *node;
  
  	down_read(&alg_types_sem);
  	list_for_each_entry(node, &alg_types, list) {
  		if (strcmp(node->type->name, name))
  			continue;
  
  		if (try_module_get(node->type->owner))
  			type = node->type;
  		break;
  	}
  	up_read(&alg_types_sem);
  
  	return type;
  }
  
  int af_alg_register_type(const struct af_alg_type *type)
  {
  	struct alg_type_list *node;
  	int err = -EEXIST;
  
  	down_write(&alg_types_sem);
  	list_for_each_entry(node, &alg_types, list) {
  		if (!strcmp(node->type->name, type->name))
  			goto unlock;
  	}
  
  	node = kmalloc(sizeof(*node), GFP_KERNEL);
  	err = -ENOMEM;
  	if (!node)
  		goto unlock;
  
  	type->ops->owner = THIS_MODULE;

  	if (type->ops_nokey)
  		type->ops_nokey->owner = THIS_MODULE;

  	node->type = type;
  	list_add(&node->list, &alg_types);
  	err = 0;
  
  unlock:
  	up_write(&alg_types_sem);
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(af_alg_register_type);
  
  int af_alg_unregister_type(const struct af_alg_type *type)
  {
  	struct alg_type_list *node;
  	int err = -ENOENT;
  
  	down_write(&alg_types_sem);
  	list_for_each_entry(node, &alg_types, list) {
  		if (strcmp(node->type->name, type->name))
  			continue;
  
  		list_del(&node->list);
  		kfree(node);
  		err = 0;
  		break;
  	}
  	up_write(&alg_types_sem);
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(af_alg_unregister_type);
  
  static void alg_do_release(const struct af_alg_type *type, void *private)
  {
  	if (!type)
  		return;
  
  	type->release(private);
  	module_put(type->owner);
  }
  
  int af_alg_release(struct socket *sock)
  {

  	if (sock->sk) {

  		sock_put(sock->sk);

  		sock->sk = NULL;
  	}

  	return 0;
  }
  EXPORT_SYMBOL_GPL(af_alg_release);

  void af_alg_release_parent(struct sock *sk)
  {
  	struct alg_sock *ask = alg_sk(sk);

  	unsigned int nokey = atomic_read(&ask->nokey_refcnt);

  
  	sk = ask->parent;
  	ask = alg_sk(sk);

  	if (nokey)
  		atomic_dec(&ask->nokey_refcnt);

  	if (atomic_dec_and_test(&ask->refcnt))

  		sock_put(sk);
  }
  EXPORT_SYMBOL_GPL(af_alg_release_parent);

  static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
  {

  	const u32 allowed = CRYPTO_ALG_KERN_DRIVER_ONLY;

  	struct sock *sk = sock->sk;
  	struct alg_sock *ask = alg_sk(sk);

  	struct sockaddr_alg_new *sa = (void *)uaddr;

  	const struct af_alg_type *type;
  	void *private;

  	int err;

  
  	if (sock->state == SS_CONNECTED)
  		return -EINVAL;

  	BUILD_BUG_ON(offsetof(struct sockaddr_alg_new, salg_name) !=
  		     offsetof(struct sockaddr_alg, salg_name));
  	BUILD_BUG_ON(offsetof(struct sockaddr_alg, salg_name) != sizeof(*sa));
  
  	if (addr_len < sizeof(*sa) + 1)

  		return -EINVAL;

  	/* If caller uses non-allowed flag, return error. */
  	if ((sa->salg_feat & ~allowed) || (sa->salg_mask & ~allowed))
  		return -EINVAL;

  	sa->salg_type[sizeof(sa->salg_type) - 1] = 0;

  	sa->salg_name[addr_len - sizeof(*sa) - 1] = 0;

  
  	type = alg_get_type(sa->salg_type);

  	if (PTR_ERR(type) == -ENOENT) {

  		request_module("algif-%s", sa->salg_type);
  		type = alg_get_type(sa->salg_type);
  	}
  
  	if (IS_ERR(type))
  		return PTR_ERR(type);

  	private = type->bind(sa->salg_name, sa->salg_feat, sa->salg_mask);

  	if (IS_ERR(private)) {
  		module_put(type->owner);
  		return PTR_ERR(private);
  	}

  	err = -EBUSY;

  	lock_sock(sk);

  	if (atomic_read(&ask->refcnt))

  		goto unlock;

  
  	swap(ask->type, type);
  	swap(ask->private, private);

  	err = 0;
  
  unlock:

  	release_sock(sk);
  
  	alg_do_release(type, private);

  	return err;

  }

  static int alg_setkey(struct sock *sk, sockptr_t ukey, unsigned int keylen)

  {
  	struct alg_sock *ask = alg_sk(sk);
  	const struct af_alg_type *type = ask->type;
  	u8 *key;
  	int err;
  
  	key = sock_kmalloc(sk, keylen, GFP_KERNEL);
  	if (!key)
  		return -ENOMEM;
  
  	err = -EFAULT;

  	if (copy_from_sockptr(key, ukey, keylen))

  		goto out;
  
  	err = type->setkey(ask->private, key, keylen);
  
  out:

  	sock_kzfree_s(sk, key, keylen);

  
  	return err;
  }
  
  static int alg_setsockopt(struct socket *sock, int level, int optname,

  			  sockptr_t optval, unsigned int optlen)

  {
  	struct sock *sk = sock->sk;
  	struct alg_sock *ask = alg_sk(sk);
  	const struct af_alg_type *type;

  	int err = -EBUSY;

  
  	lock_sock(sk);

  	if (atomic_read(&ask->refcnt) != atomic_read(&ask->nokey_refcnt))

  		goto unlock;

  	type = ask->type;

  	err = -ENOPROTOOPT;

  	if (level != SOL_ALG || !type)
  		goto unlock;
  
  	switch (optname) {
  	case ALG_SET_KEY:
  		if (sock->state == SS_CONNECTED)
  			goto unlock;
  		if (!type->setkey)
  			goto unlock;
  
  		err = alg_setkey(sk, optval, optlen);

  		break;
  	case ALG_SET_AEAD_AUTHSIZE:
  		if (sock->state == SS_CONNECTED)
  			goto unlock;
  		if (!type->setauthsize)
  			goto unlock;
  		err = type->setauthsize(ask->private, optlen);

  		break;
  	case ALG_SET_DRBG_ENTROPY:
  		if (sock->state == SS_CONNECTED)
  			goto unlock;
  		if (!type->setentropy)
  			goto unlock;
  
  		err = type->setentropy(ask->private, optval, optlen);

  	}
  
  unlock:
  	release_sock(sk);
  
  	return err;
  }

  int af_alg_accept(struct sock *sk, struct socket *newsock, bool kern)

  {
  	struct alg_sock *ask = alg_sk(sk);
  	const struct af_alg_type *type;
  	struct sock *sk2;

  	unsigned int nokey;

  	int err;
  
  	lock_sock(sk);
  	type = ask->type;
  
  	err = -EINVAL;
  	if (!type)
  		goto unlock;

  	sk2 = sk_alloc(sock_net(sk), PF_ALG, GFP_KERNEL, &alg_proto, kern);

  	err = -ENOMEM;
  	if (!sk2)
  		goto unlock;
  
  	sock_init_data(newsock, sk2);

  	security_sock_graft(sk2, newsock);

  	security_sk_clone(sk, sk2);

  	/*
  	 * newsock->ops assigned here to allow type->accept call to override
  	 * them when required.
  	 */
  	newsock->ops = type->ops;

  	err = type->accept(ask->private, sk2);

  
  	nokey = err == -ENOKEY;
  	if (nokey && type->accept_nokey)
  		err = type->accept_nokey(ask->private, sk2);

  	if (err)

  		goto unlock;

  	if (atomic_inc_return_relaxed(&ask->refcnt) == 1)

  		sock_hold(sk);

  	if (nokey) {
  		atomic_inc(&ask->nokey_refcnt);
  		atomic_set(&alg_sk(sk2)->nokey_refcnt, 1);
  	}

  	alg_sk(sk2)->parent = sk;
  	alg_sk(sk2)->type = type;

  	newsock->state = SS_CONNECTED;

  	if (nokey)
  		newsock->ops = type->ops_nokey;

  	err = 0;
  
  unlock:
  	release_sock(sk);
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(af_alg_accept);

  static int alg_accept(struct socket *sock, struct socket *newsock, int flags,
  		      bool kern)

  {

  	return af_alg_accept(sock->sk, newsock, kern);

  }
  
  static const struct proto_ops alg_proto_ops = {
  	.family		=	PF_ALG,
  	.owner		=	THIS_MODULE,
  
  	.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,
  	.sendpage	=	sock_no_sendpage,
  	.sendmsg	=	sock_no_sendmsg,
  	.recvmsg	=	sock_no_recvmsg,

  
  	.bind		=	alg_bind,
  	.release	=	af_alg_release,
  	.setsockopt	=	alg_setsockopt,
  	.accept		=	alg_accept,
  };
  
  static void alg_sock_destruct(struct sock *sk)
  {
  	struct alg_sock *ask = alg_sk(sk);
  
  	alg_do_release(ask->type, ask->private);
  }
  
  static int alg_create(struct net *net, struct socket *sock, int protocol,
  		      int kern)
  {
  	struct sock *sk;
  	int err;
  
  	if (sock->type != SOCK_SEQPACKET)
  		return -ESOCKTNOSUPPORT;
  	if (protocol != 0)
  		return -EPROTONOSUPPORT;
  
  	err = -ENOMEM;

  	sk = sk_alloc(net, PF_ALG, GFP_KERNEL, &alg_proto, kern);

  	if (!sk)
  		goto out;
  
  	sock->ops = &alg_proto_ops;
  	sock_init_data(sock, sk);

  	sk->sk_destruct = alg_sock_destruct;
  
  	return 0;
  out:
  	return err;
  }
  
  static const struct net_proto_family alg_family = {
  	.family	=	PF_ALG,
  	.create	=	alg_create,
  	.owner	=	THIS_MODULE,
  };

  int af_alg_make_sg(struct af_alg_sgl *sgl, struct iov_iter *iter, int len)

  {

  	size_t off;
  	ssize_t n;
  	int npages, i;

  	n = iov_iter_get_pages(iter, sgl->pages, len, ALG_MAX_PAGES, &off);
  	if (n < 0)
  		return n;

  	npages = (off + n + PAGE_SIZE - 1) >> PAGE_SHIFT;

  	if (WARN_ON(npages == 0))

  		return -EINVAL;

  	/* Add one extra for linking */
  	sg_init_table(sgl->sg, npages + 1);

  	for (i = 0, len = n; i < npages; i++) {

  		int plen = min_t(int, len, PAGE_SIZE - off);
  
  		sg_set_page(sgl->sg + i, sgl->pages[i], plen, off);
  
  		off = 0;
  		len -= plen;

  	}

  	sg_mark_end(sgl->sg + npages - 1);
  	sgl->npages = npages;

  	return n;

  }
  EXPORT_SYMBOL_GPL(af_alg_make_sg);

  static void af_alg_link_sg(struct af_alg_sgl *sgl_prev,
  			   struct af_alg_sgl *sgl_new)

  {
  	sg_unmark_end(sgl_prev->sg + sgl_prev->npages - 1);
  	sg_chain(sgl_prev->sg, sgl_prev->npages + 1, sgl_new->sg);
  }

  void af_alg_free_sg(struct af_alg_sgl *sgl)
  {
  	int i;

  	for (i = 0; i < sgl->npages; i++)

  		put_page(sgl->pages[i]);

  }
  EXPORT_SYMBOL_GPL(af_alg_free_sg);

  static int af_alg_cmsg_send(struct msghdr *msg, struct af_alg_control *con)

  {
  	struct cmsghdr *cmsg;

  	for_each_cmsghdr(cmsg, msg) {

  		if (!CMSG_OK(msg, cmsg))
  			return -EINVAL;
  		if (cmsg->cmsg_level != SOL_ALG)
  			continue;

  		switch (cmsg->cmsg_type) {

  		case ALG_SET_IV:
  			if (cmsg->cmsg_len < CMSG_LEN(sizeof(*con->iv)))
  				return -EINVAL;
  			con->iv = (void *)CMSG_DATA(cmsg);
  			if (cmsg->cmsg_len < CMSG_LEN(con->iv->ivlen +
  						      sizeof(*con->iv)))
  				return -EINVAL;
  			break;
  
  		case ALG_SET_OP:
  			if (cmsg->cmsg_len < CMSG_LEN(sizeof(u32)))
  				return -EINVAL;
  			con->op = *(u32 *)CMSG_DATA(cmsg);
  			break;

  		case ALG_SET_AEAD_ASSOCLEN:
  			if (cmsg->cmsg_len < CMSG_LEN(sizeof(u32)))
  				return -EINVAL;
  			con->aead_assoclen = *(u32 *)CMSG_DATA(cmsg);
  			break;

  		default:
  			return -EINVAL;
  		}
  	}
  
  	return 0;
  }

  /**
   * af_alg_alloc_tsgl - allocate the TX SGL
   *
   * @sk socket of connection to user space
   * @return: 0 upon success, < 0 upon error
   */

  static int af_alg_alloc_tsgl(struct sock *sk)

  {
  	struct alg_sock *ask = alg_sk(sk);
  	struct af_alg_ctx *ctx = ask->private;
  	struct af_alg_tsgl *sgl;
  	struct scatterlist *sg = NULL;
  
  	sgl = list_entry(ctx->tsgl_list.prev, struct af_alg_tsgl, list);
  	if (!list_empty(&ctx->tsgl_list))
  		sg = sgl->sg;
  
  	if (!sg || sgl->cur >= MAX_SGL_ENTS) {

  		sgl = sock_kmalloc(sk,
  				   struct_size(sgl, sg, (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_list);
  	}
  
  	return 0;
  }

  
  /**
   * aead_count_tsgl - Count number of TX SG entries
   *
   * The counting starts from the beginning of the SGL to @bytes. If
   * an offset is provided, the counting of the SG entries starts at the offset.
   *
   * @sk socket of connection to user space
   * @bytes Count the number of SG entries holding given number of bytes.
   * @offset Start the counting of SG entries from the given offset.
   * @return Number of TX SG entries found given the constraints
   */
  unsigned int af_alg_count_tsgl(struct sock *sk, size_t bytes, size_t offset)
  {

  	const struct alg_sock *ask = alg_sk(sk);
  	const struct af_alg_ctx *ctx = ask->private;
  	const struct af_alg_tsgl *sgl;

  	unsigned int i;
  	unsigned int sgl_count = 0;
  
  	if (!bytes)
  		return 0;

  	list_for_each_entry(sgl, &ctx->tsgl_list, list) {
  		const struct scatterlist *sg = sgl->sg;

  
  		for (i = 0; i < sgl->cur; i++) {
  			size_t bytes_count;
  
  			/* Skip offset */
  			if (offset >= sg[i].length) {
  				offset -= sg[i].length;
  				bytes -= sg[i].length;
  				continue;
  			}
  
  			bytes_count = sg[i].length - offset;
  
  			offset = 0;
  			sgl_count++;
  
  			/* If we have seen requested number of bytes, stop */
  			if (bytes_count >= bytes)
  				return sgl_count;
  
  			bytes -= bytes_count;
  		}
  	}
  
  	return sgl_count;
  }
  EXPORT_SYMBOL_GPL(af_alg_count_tsgl);
  
  /**
   * aead_pull_tsgl - Release the specified buffers from TX SGL
   *
   * If @dst is non-null, reassign the pages to dst. The caller must release
   * the pages. If @dst_offset is given only reassign the pages to @dst starting
   * at the @dst_offset (byte). The caller must ensure that @dst is large
   * enough (e.g. by using af_alg_count_tsgl with the same offset).
   *
   * @sk socket of connection to user space
   * @used Number of bytes to pull from TX SGL
   * @dst If non-NULL, buffer is reassigned to dst SGL instead of releasing. The
   *	caller must release the buffers in dst.
   * @dst_offset Reassign the TX SGL from given offset. All buffers before
   *	       reaching the offset is released.
   */
  void af_alg_pull_tsgl(struct sock *sk, size_t used, struct scatterlist *dst,
  		      size_t dst_offset)
  {
  	struct alg_sock *ask = alg_sk(sk);
  	struct af_alg_ctx *ctx = ask->private;
  	struct af_alg_tsgl *sgl;
  	struct scatterlist *sg;

  	unsigned int i, j = 0;

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

  		for (i = 0; i < sgl->cur; i++) {

  			size_t plen = min_t(size_t, used, sg[i].length);
  			struct page *page = sg_page(sg + i);
  
  			if (!page)
  				continue;
  
  			/*
  			 * Assumption: caller created af_alg_count_tsgl(len)
  			 * SG entries in dst.
  			 */
  			if (dst) {
  				if (dst_offset >= plen) {
  					/* discard page before offset */
  					dst_offset -= plen;

  				} else {
  					/* reassign page to dst after offset */

  					get_page(page);

  					sg_set_page(dst + j, page,
  						    plen - dst_offset,
  						    sg[i].offset + dst_offset);
  					dst_offset = 0;
  					j++;
  				}
  			}
  
  			sg[i].length -= plen;
  			sg[i].offset += plen;
  
  			used -= plen;
  			ctx->used -= plen;
  
  			if (sg[i].length)
  				return;

  			put_page(page);

  			sg_assign_page(sg + i, NULL);
  		}
  
  		list_del(&sgl->list);

  		sock_kfree_s(sk, sgl, struct_size(sgl, sg, MAX_SGL_ENTS + 1));

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

  	ctx->init = ctx->more;

  }
  EXPORT_SYMBOL_GPL(af_alg_pull_tsgl);
  
  /**
   * af_alg_free_areq_sgls - Release TX and RX SGLs of the request
   *
   * @areq Request holding the TX and RX SGL
   */

  static void af_alg_free_areq_sgls(struct af_alg_async_req *areq)

  {
  	struct sock *sk = areq->sk;
  	struct alg_sock *ask = alg_sk(sk);
  	struct af_alg_ctx *ctx = ask->private;
  	struct af_alg_rsgl *rsgl, *tmp;
  	struct scatterlist *tsgl;
  	struct scatterlist *sg;
  	unsigned int i;
  
  	list_for_each_entry_safe(rsgl, tmp, &areq->rsgl_list, list) {

  		atomic_sub(rsgl->sg_num_bytes, &ctx->rcvused);

  		af_alg_free_sg(&rsgl->sgl);
  		list_del(&rsgl->list);
  		if (rsgl != &areq->first_rsgl)
  			sock_kfree_s(sk, rsgl, sizeof(*rsgl));
  	}
  
  	tsgl = areq->tsgl;

  	if (tsgl) {
  		for_each_sg(tsgl, sg, areq->tsgl_entries, i) {
  			if (!sg_page(sg))
  				continue;
  			put_page(sg_page(sg));
  		}

  		sock_kfree_s(sk, tsgl, areq->tsgl_entries * sizeof(*tsgl));

  	}

  }

  
  /**
   * af_alg_wait_for_wmem - wait for availability of writable memory
   *
   * @sk socket of connection to user space
   * @flags If MSG_DONTWAIT is set, then only report if function would sleep
   * @return 0 when writable memory is available, < 0 upon error
   */

  static int af_alg_wait_for_wmem(struct sock *sk, unsigned int 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, af_alg_writable(sk), &wait)) {
  			err = 0;
  			break;
  		}
  	}
  	remove_wait_queue(sk_sleep(sk), &wait);
  
  	return err;
  }

  
  /**
   * af_alg_wmem_wakeup - wakeup caller when writable memory is available
   *
   * @sk socket of connection to user space
   */
  void af_alg_wmem_wakeup(struct sock *sk)
  {
  	struct socket_wq *wq;
  
  	if (!af_alg_writable(sk))
  		return;
  
  	rcu_read_lock();
  	wq = rcu_dereference(sk->sk_wq);
  	if (skwq_has_sleeper(wq))

  		wake_up_interruptible_sync_poll(&wq->wait, EPOLLIN |
  							   EPOLLRDNORM |
  							   EPOLLRDBAND);

  	sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
  	rcu_read_unlock();
  }
  EXPORT_SYMBOL_GPL(af_alg_wmem_wakeup);
  
  /**
   * af_alg_wait_for_data - wait for availability of TX data
   *
   * @sk socket of connection to user space
   * @flags If MSG_DONTWAIT is set, then only report if function would sleep

   * @min Set to minimum request size if partial requests are allowed.

   * @return 0 when writable memory is available, < 0 upon error
   */

  int af_alg_wait_for_data(struct sock *sk, unsigned flags, unsigned min)

  {
  	DEFINE_WAIT_FUNC(wait, woken_wake_function);
  	struct alg_sock *ask = alg_sk(sk);
  	struct af_alg_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->init && (!ctx->more ||
  						(min && ctx->used >= min)),

  				  &wait)) {
  			err = 0;
  			break;
  		}
  	}
  	remove_wait_queue(sk_sleep(sk), &wait);
  
  	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(af_alg_wait_for_data);
  
  /**
   * af_alg_data_wakeup - wakeup caller when new data can be sent to kernel
   *
   * @sk socket of connection to user space
   */

  static void af_alg_data_wakeup(struct sock *sk)

  {
  	struct alg_sock *ask = alg_sk(sk);
  	struct af_alg_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, EPOLLOUT |
  							   EPOLLRDNORM |
  							   EPOLLRDBAND);

  	sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
  	rcu_read_unlock();
  }

  
  /**
   * af_alg_sendmsg - implementation of sendmsg system call handler
   *
   * The sendmsg system call handler obtains the user data and stores it
   * in ctx->tsgl_list. This implies allocation of the required numbers of
   * struct af_alg_tsgl.
   *
   * In addition, the ctx is filled with the information sent via CMSG.
   *
   * @sock socket of connection to user space
   * @msg message from user space
   * @size size of message from user space
   * @ivsize the size of the IV for the cipher operation to verify that the
   *	   user-space-provided IV has the right size
   * @return the number of copied data upon success, < 0 upon error
   */
  int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
  		   unsigned int ivsize)
  {
  	struct sock *sk = sock->sk;
  	struct alg_sock *ask = alg_sk(sk);
  	struct af_alg_ctx *ctx = ask->private;
  	struct af_alg_tsgl *sgl;
  	struct af_alg_control con = {};
  	long copied = 0;

  	bool enc = false;
  	bool init = false;

  	int err = 0;
  
  	if (msg->msg_controllen) {
  		err = af_alg_cmsg_send(msg, &con);
  		if (err)
  			return err;

  		init = true;

  		switch (con.op) {
  		case ALG_OP_ENCRYPT:

  			enc = true;

  			break;
  		case ALG_OP_DECRYPT:

  			enc = false;

  			break;
  		default:
  			return -EINVAL;
  		}
  
  		if (con.iv && con.iv->ivlen != ivsize)
  			return -EINVAL;
  	}
  
  	lock_sock(sk);

  	if (ctx->init && !ctx->more) {
  		if (ctx->used) {
  			err = -EINVAL;
  			goto unlock;
  		}
  
  		pr_info_once(
  			"%s sent an empty control message without MSG_MORE.
  ",
  			current->comm);

  	}

  	ctx->init = true;

  
  	if (init) {
  		ctx->enc = enc;
  		if (con.iv)
  			memcpy(ctx->iv, con.iv->iv, ivsize);
  
  		ctx->aead_assoclen = con.aead_assoclen;
  	}
  
  	while (size) {
  		struct scatterlist *sg;
  		size_t len = size;
  		size_t plen;
  
  		/* use the existing memory in an allocated page */
  		if (ctx->merge) {
  			sgl = list_entry(ctx->tsgl_list.prev,
  					 struct af_alg_tsgl, list);
  			sg = sgl->sg + sgl->cur - 1;
  			len = min_t(size_t, 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 (!af_alg_writable(sk)) {
  			err = af_alg_wait_for_wmem(sk, msg->msg_flags);
  			if (err)
  				goto unlock;
  		}
  
  		/* allocate a new page */
  		len = min_t(unsigned long, len, af_alg_sndbuf(sk));
  
  		err = af_alg_alloc_tsgl(sk);
  		if (err)
  			goto unlock;
  
  		sgl = list_entry(ctx->tsgl_list.prev, struct af_alg_tsgl,
  				 list);
  		sg = sgl->sg;
  		if (sgl->cur)
  			sg_unmark_end(sg + sgl->cur - 1);
  
  		do {
  			unsigned int i = sgl->cur;
  
  			plen = min_t(size_t, len, PAGE_SIZE);
  
  			sg_assign_page(sg + i, alloc_page(GFP_KERNEL));
  			if (!sg_page(sg + i)) {
  				err = -ENOMEM;
  				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:
  	af_alg_data_wakeup(sk);
  	release_sock(sk);
  
  	return copied ?: err;
  }
  EXPORT_SYMBOL_GPL(af_alg_sendmsg);
  
  /**
   * af_alg_sendpage - sendpage system call handler
   *
   * This is a generic implementation of sendpage to fill ctx->tsgl_list.
   */
  ssize_t af_alg_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 af_alg_ctx *ctx = ask->private;
  	struct af_alg_tsgl *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 (!af_alg_writable(sk)) {
  		err = af_alg_wait_for_wmem(sk, flags);
  		if (err)
  			goto unlock;
  	}
  
  	err = af_alg_alloc_tsgl(sk);
  	if (err)
  		goto unlock;
  
  	ctx->merge = 0;
  	sgl = list_entry(ctx->tsgl_list.prev, struct af_alg_tsgl, 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:
  	af_alg_data_wakeup(sk);
  	release_sock(sk);
  
  	return err ?: size;
  }
  EXPORT_SYMBOL_GPL(af_alg_sendpage);
  
  /**

   * af_alg_free_resources - release resources required for crypto request
   */
  void af_alg_free_resources(struct af_alg_async_req *areq)
  {
  	struct sock *sk = areq->sk;
  
  	af_alg_free_areq_sgls(areq);
  	sock_kfree_s(sk, areq, areq->areqlen);
  }
  EXPORT_SYMBOL_GPL(af_alg_free_resources);
  
  /**

   * af_alg_async_cb - AIO callback handler
   *
   * This handler cleans up the struct af_alg_async_req upon completion of the
   * AIO operation.
   *
   * The number of bytes to be generated with the AIO operation must be set
   * in areq->outlen before the AIO callback handler is invoked.
   */
  void af_alg_async_cb(struct crypto_async_request *_req, int err)
  {
  	struct af_alg_async_req *areq = _req->data;
  	struct sock *sk = areq->sk;
  	struct kiocb *iocb = areq->iocb;
  	unsigned int resultlen;

  	/* Buffer size written by crypto operation. */
  	resultlen = areq->outlen;

  	af_alg_free_resources(areq);
  	sock_put(sk);

  	iocb->ki_complete(iocb, err ? err : (int)resultlen, 0);

  }
  EXPORT_SYMBOL_GPL(af_alg_async_cb);

  /**
   * af_alg_poll - poll system call handler
   */
  __poll_t af_alg_poll(struct file *file, struct socket *sock,
  			 poll_table *wait)

  {
  	struct sock *sk = sock->sk;
  	struct alg_sock *ask = alg_sk(sk);
  	struct af_alg_ctx *ctx = ask->private;

  	__poll_t mask;

  	sock_poll_wait(file, sock, wait);

  	mask = 0;

  
  	if (!ctx->more || ctx->used)

  		mask |= EPOLLIN | EPOLLRDNORM;

  
  	if (af_alg_writable(sk))

  		mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;

  
  	return mask;
  }

  EXPORT_SYMBOL_GPL(af_alg_poll);

  
  /**
   * af_alg_alloc_areq - allocate struct af_alg_async_req
   *
   * @sk socket of connection to user space
   * @areqlen size of struct af_alg_async_req + crypto_*_reqsize
   * @return allocated data structure or ERR_PTR upon error
   */
  struct af_alg_async_req *af_alg_alloc_areq(struct sock *sk,
  					   unsigned int areqlen)
  {
  	struct af_alg_async_req *areq = sock_kmalloc(sk, areqlen, GFP_KERNEL);
  
  	if (unlikely(!areq))
  		return ERR_PTR(-ENOMEM);
  
  	areq->areqlen = areqlen;
  	areq->sk = sk;
  	areq->last_rsgl = NULL;
  	INIT_LIST_HEAD(&areq->rsgl_list);
  	areq->tsgl = NULL;
  	areq->tsgl_entries = 0;
  
  	return areq;
  }
  EXPORT_SYMBOL_GPL(af_alg_alloc_areq);
  
  /**
   * af_alg_get_rsgl - create the RX SGL for the output data from the crypto
   *		     operation
   *
   * @sk socket of connection to user space
   * @msg user space message
   * @flags flags used to invoke recvmsg with
   * @areq instance of the cryptographic request that will hold the RX SGL
   * @maxsize maximum number of bytes to be pulled from user space
   * @outlen number of bytes in the RX SGL
   * @return 0 on success, < 0 upon error
   */
  int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
  		    struct af_alg_async_req *areq, size_t maxsize,
  		    size_t *outlen)
  {
  	struct alg_sock *ask = alg_sk(sk);
  	struct af_alg_ctx *ctx = ask->private;
  	size_t len = 0;
  
  	while (maxsize > len && msg_data_left(msg)) {
  		struct af_alg_rsgl *rsgl;
  		size_t seglen;
  		int err;
  
  		/* limit the amount of readable buffers */
  		if (!af_alg_readable(sk))
  			break;

  		seglen = min_t(size_t, (maxsize - len),
  			       msg_data_left(msg));
  
  		if (list_empty(&areq->rsgl_list)) {
  			rsgl = &areq->first_rsgl;
  		} else {
  			rsgl = sock_kmalloc(sk, sizeof(*rsgl), GFP_KERNEL);
  			if (unlikely(!rsgl))
  				return -ENOMEM;
  		}
  
  		rsgl->sgl.npages = 0;
  		list_add_tail(&rsgl->list, &areq->rsgl_list);
  
  		/* make one iovec available as scatterlist */
  		err = af_alg_make_sg(&rsgl->sgl, &msg->msg_iter, seglen);

  		if (err < 0) {
  			rsgl->sg_num_bytes = 0;

  			return err;

  		}

  
  		/* chain the new scatterlist with previous one */
  		if (areq->last_rsgl)
  			af_alg_link_sg(&areq->last_rsgl->sgl, &rsgl->sgl);
  
  		areq->last_rsgl = rsgl;
  		len += err;

  		atomic_add(err, &ctx->rcvused);

  		rsgl->sg_num_bytes = err;
  		iov_iter_advance(&msg->msg_iter, err);
  	}
  
  	*outlen = len;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(af_alg_get_rsgl);

  static int __init af_alg_init(void)
  {
  	int err = proto_register(&alg_proto, 0);
  
  	if (err)
  		goto out;
  
  	err = sock_register(&alg_family);
  	if (err != 0)
  		goto out_unregister_proto;
  
  out:
  	return err;
  
  out_unregister_proto:
  	proto_unregister(&alg_proto);
  	goto out;
  }
  
  static void __exit af_alg_exit(void)
  {
  	sock_unregister(PF_ALG);
  	proto_unregister(&alg_proto);
  }
  
  module_init(af_alg_init);
  module_exit(af_alg_exit);
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_NETPROTO(AF_ALG);