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/*

 * 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;

	unsigned used;

	unsigned int len;

	bool more;

	bool merge;

	bool enc;

	struct ablkcipher_request req;

};

#define MAX_SGL_ENTS ((PAGE_SIZE - sizeof(struct skcipher_sg_list)) / \

		      sizeof(struct scatterlist) - 1)

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)

{

	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;

			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);

}

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 kiocb *unused, 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;

	int err;

	int i;

	if (msg->msg_controllen) {

		err = af_alg_cmsg_send(msg, &con);

		if (err)

			return err;

		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 (!ctx->used) {

		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_fromiovec(page_address(sg_page(sg)) +

					       sg->offset + sg->length,

					       msg->msg_iov, 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;

		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_fromiovec(page_address(sg_page(sg + i)),

					       msg->msg_iov, 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);

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

	}

	err = 0;

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

	if (!ctx->more && !list_empty(&ctx->tsgl))

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

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;

	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);

	get_page(page);

	sg_set_page(sgl->sg + sgl->cur, page, size, offset);

	sgl->cur++;

	ctx->used += size;

done:

	ctx->more = flags & MSG_MORE;

	if (!ctx->more && !list_empty(&ctx->tsgl))

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

unlock:

	skcipher_data_wakeup(sk);

	release_sock(sk);

	return err ?: size;

}

static int skcipher_recvmsg(struct kiocb *unused, struct socket *sock,

			    struct msghdr *msg, size_t ignored, 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;

	unsigned long iovlen;

	struct iovec *iov;

	int err = -EAGAIN;

	int used;

	long copied = 0;

	lock_sock(sk);

	for (iov = msg->msg_iov, iovlen = msg->msg_iovlen; iovlen > 0;

	     iovlen--, iov++) {

		unsigned long seglen = iov->iov_len;

		char __user *from = iov->iov_base;

		while (seglen) {

			sgl = list_first_entry(&ctx->tsgl,

					       struct skcipher_sg_list, list);

			sg = sgl->sg;

			while (!sg->length)

				sg++;

			used = ctx->used;

			if (!used) {

				err = skcipher_wait_for_data(sk, flags);

				if (err)

					goto unlock;

			}

			used = min_t(unsigned long, used, seglen);

			used = af_alg_make_sg(&ctx->rsgl, from, used, 1);

			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;

			from += used;

			seglen -= used;

			skcipher_pull_sgl(sk, used);

		}

	}

	err = 0;

unlock:

	skcipher_wmem_wakeup(sk);

	release_sock(sk);

	return copied ?: err;

}

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_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);

	skcipher_free_sgl(sk);

	sock_kfree_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;

	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");