path: root/crypto/algif_aead.c

/*
 * algif_aead: User-space interface for AEAD algorithms
 *
 * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de>
 *
 * This file provides the user-space API for AEAD ciphers.
 *
 * 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.
 *
 * The following concept of the memory management is used:
 *
 * The kernel maintains two SGLs, the TX SGL and the RX SGL. The TX SGL is
 * filled by user space with the data submitted via sendpage/sendmsg. Filling
 * up the TX SGL does not cause a crypto operation -- the data will only be
 * tracked by the kernel. Upon receipt of one recvmsg call, the caller must
 * provide a buffer which is tracked with the RX SGL.
 *
 * During the processing of the recvmsg operation, the cipher request is
 * allocated and prepared. As part of the recvmsg operation, the processed
 * TX buffers are extracted from the TX SGL into a separate SGL.
 *
 * After the completion of the crypto operation, the RX SGL and the cipher
 * request is released. The extracted TX SGL parts are released together with
 * the RX SGL release.
 */

#include <crypto/internal/aead.h>
#include <crypto/scatterwalk.h>
#include <crypto/if_alg.h>
#include <crypto/skcipher.h>
#include <crypto/null.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 aead_tsgl {
	struct list_head list;
	unsigned int cur;		/* Last processed SG entry */
	struct scatterlist sg[0];	/* Array of SGs forming the SGL */
};

struct aead_rsgl {
	struct af_alg_sgl sgl;
	struct list_head list;
	size_t sg_num_bytes;		/* Bytes of data in that SGL */
};

struct aead_async_req {
	struct kiocb *iocb;
	struct sock *sk;

	struct aead_rsgl first_rsgl;	/* First RX SG */
	struct list_head rsgl_list;	/* Track RX SGs */

	struct scatterlist *tsgl;	/* priv. TX SGL of buffers to process */
	unsigned int tsgl_entries;	/* number of entries in priv. TX SGL */

	unsigned int outlen;		/* Filled output buf length */

	unsigned int areqlen;		/* Length of this data struct */
	struct aead_request aead_req;	/* req ctx trails this struct */
};

struct aead_tfm {
	struct crypto_aead *aead;
	bool has_key;
	struct crypto_skcipher *null_tfm;
};

struct aead_ctx {
	struct list_head tsgl_list;	/* Link to TX SGL */

	void *iv;
	size_t aead_assoclen;

	struct af_alg_completion completion;	/* sync work queue */

	size_t used;		/* TX bytes sent to kernel */
	size_t rcvused;		/* total RX bytes to be processed by kernel */

	bool more;		/* More data to be expected? */
	bool merge;		/* Merge new data into existing SG */
	bool enc;		/* Crypto operation: enc, dec */

	unsigned int len;	/* Length of allocated memory for this struct */
};

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

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

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

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

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

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

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

static inline bool aead_sufficient_data(struct sock *sk)
{
	struct alg_sock *ask = alg_sk(sk);
	struct sock *psk = ask->parent;
	struct alg_sock *pask = alg_sk(psk);
	struct aead_ctx *ctx = ask->private;
	struct aead_tfm *aeadc = pask->private;
	struct crypto_aead *tfm = aeadc->aead;
	unsigned int as = crypto_aead_authsize(tfm);

	/*
	 * The minimum amount of memory needed for an AEAD cipher is
	 * the AAD and in case of decryption the tag.
	 */
	return ctx->used >= ctx->aead_assoclen + (ctx->enc ? 0 : as);
}

static int aead_alloc_tsgl(struct sock *sk)
{
	struct alg_sock *ask = alg_sk(sk);
	struct aead_ctx *ctx = ask->private;
	struct aead_tsgl *sgl;
	struct scatterlist *sg = NULL;

	sgl = list_entry(ctx->tsgl_list.prev, struct aead_tsgl, list);
	if (!list_empty(&ctx->tsgl_list))
		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_list);
	}

	return 0;
}

/**
 * Count number of SG entries from the beginning of the SGL to @bytes. If
 * an offset is provided, the counting of the SG entries starts at the offset.
 */
static unsigned int aead_count_tsgl(struct sock *sk, size_t bytes,
				    size_t offset)
{
	struct alg_sock *ask = alg_sk(sk);
	struct aead_ctx *ctx = ask->private;
	struct aead_tsgl *sgl, *tmp;
	unsigned int i;
	unsigned int sgl_count = 0;

	if (!bytes)
		return 0;

	list_for_each_entry_safe(sgl, tmp, &ctx->tsgl_list, list) {
		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;
}

/**
 * Release the specified buffers from TX SGL pointed to by ctx->tsgl_list for
 * @used bytes.
 *
 * 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 aead_count_tsgl with the same offset).
 */
static void aead_pull_tsgl(struct sock *sk, size_t used,
			   struct scatterlist *dst, size_t dst_offset)
{
	struct alg_sock *ask = alg_sk(sk);
	struct aead_ctx *ctx = ask->private;
	struct aead_tsgl *sgl;
	struct scatterlist *sg;
	unsigned int i, j;

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

		for (i = 0, j = 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 aead_count_tsgl(len)
			 * SG entries in dst.
			 */
			if (dst) {
				if (dst_offset >= plen) {
					/* discard page before offset */
					dst_offset -= plen;
					put_page(page);
				} else {
					/* reassign page to dst after offset */
					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;

			if (!dst)
				put_page(page);

			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 aead_free_areq_sgls(struct aead_async_req *areq)
{
	struct sock *sk = areq->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct aead_ctx *ctx = ask->private;
	struct aead_rsgl *rsgl, *tmp;
	struct scatterlist *tsgl;
	struct scatterlist *sg;
	unsigned int i;

	list_for_each_entry_safe(rsgl, tmp, &areq->rsgl_list, list) {
		ctx->rcvused -= rsgl->sg_num_bytes;
		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;
	for_each_sg(tsgl, sg, areq->tsgl_entries, i) {
		if (!sg_page(sg))
			continue;
		put_page(sg_page(sg));
	}

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

static int aead_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, aead_writable(sk), &wait)) {
			err = 0;
			break;
		}
	}
	remove_wait_queue(sk_sleep(sk), &wait);

	return err;
}

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

	if (!aead_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 aead_wait_for_data(struct sock *sk, unsigned flags)
{
	DEFINE_WAIT_FUNC(wait, woken_wake_function);
	struct alg_sock *ask = alg_sk(sk);
	struct aead_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->more, &wait)) {
			err = 0;
			break;
		}
	}
	remove_wait_queue(sk_sleep(sk), &wait);

	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);

	return err;
}

static void aead_data_wakeup(struct sock *sk)
{
	struct alg_sock *ask = alg_sk(sk);
	struct aead_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 aead_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 aead_ctx *ctx = ask->private;
	struct aead_tfm *aeadc = pask->private;
	struct crypto_aead *tfm = aeadc->aead;
	unsigned int ivsize = crypto_aead_ivsize(tfm);
	struct aead_tsgl *sgl;
	struct af_alg_control con = {};
	long copied = 0;
	bool enc = 0;
	bool init = 0;
	int err = 0;

	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;
	}

	lock_sock(sk);
	if (!ctx->more && ctx->used) {
		err = -EINVAL;
		goto unlock;
	}

	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 aead_tsgl, 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 (!aead_writable(sk)) {
			err = aead_wait_for_wmem(sk, msg->msg_flags);
			if (err)
				goto unlock;
		}

		/* allocate a new page */
		len = min_t(unsigned long, size, aead_sndbuf(sk));

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

		sgl = list_entry(ctx->tsgl_list.prev, struct aead_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:
	aead_data_wakeup(sk);
	release_sock(sk);

	return err ?: copied;
}

static ssize_t aead_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 aead_ctx *ctx = ask->private;
	struct aead_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 (!aead_writable(sk)) {
		err = aead_wait_for_wmem(sk, flags);
		if (err)
			goto unlock;
	}

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

	ctx->merge = 0;
	sgl = list_entry(ctx->tsgl_list.prev, struct aead_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;

	err = 0;

done:
	ctx->more = flags & MSG_MORE;
unlock:
	aead_data_wakeup(sk);
	release_sock(sk);

	return err ?: size;
}

static void aead_async_cb(struct crypto_async_request *_req, int err)
{
	struct aead_async_req *areq = _req->data;
	struct sock *sk = areq->sk;
	struct kiocb *iocb = areq->iocb;
	unsigned int resultlen;

	lock_sock(sk);

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

	aead_free_areq_sgls(areq);
	sock_kfree_s(sk, areq, areq->areqlen);
	__sock_put(sk);

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

	release_sock(sk);
}

static int crypto_aead_copy_sgl(struct crypto_skcipher *null_tfm,
				struct scatterlist *src,
				struct scatterlist *dst, unsigned int len)
{
	SKCIPHER_REQUEST_ON_STACK(skreq, null_tfm);

	skcipher_request_set_tfm(skreq, null_tfm);
	skcipher_request_set_callback(skreq, CRYPTO_TFM_REQ_MAY_BACKLOG,
				      NULL, NULL);
	skcipher_request_set_crypt(skreq, src, dst, len, NULL);

	return crypto_skcipher_encrypt(skreq);
}

static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
			 size_t ignored, 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 aead_ctx *ctx = ask->private;
	struct aead_tfm *aeadc = pask->private;
	struct crypto_aead *tfm = aeadc->aead;
	struct crypto_skcipher *null_tfm = aeadc->null_tfm;
	unsigned int as = crypto_aead_authsize(tfm);
	unsigned int areqlen =
		sizeof(struct aead_async_req) + crypto_aead_reqsize(tfm);
	struct aead_async_req *areq;
	struct aead_rsgl *last_rsgl = NULL;
	struct aead_tsgl *tsgl;
	struct scatterlist *src;
	int err = 0;
	size_t used = 0;		/* [in]  TX bufs to be en/decrypted */
	size_t outlen = 0;		/* [out] RX bufs produced by kernel */
	size_t usedpages = 0;		/* [in]  RX bufs to be used from user */
	size_t processed = 0;		/* [in]  TX bufs to be consumed */

	/*
	 * Data length provided by caller via sendmsg/sendpage that has not
	 * yet been processed.
	 */
	used = ctx->used;

	/*
	 * Make sure sufficient data is present -- note, the same check is
	 * is also present in sendmsg/sendpage. The checks in sendpage/sendmsg
	 * shall provide an information to the data sender that something is
	 * wrong, but they are irrelevant to maintain the kernel integrity.
	 * We need this check here too in case user space decides to not honor
	 * the error message in sendmsg/sendpage and still call recvmsg. This
	 * check here protects the kernel integrity.
	 */
	if (!aead_sufficient_data(sk))
		return -EINVAL;

	/*
	 * Calculate the minimum output buffer size holding the result of the
	 * cipher operation. When encrypting data, the receiving buffer is
	 * larger by the tag length compared to the input buffer as the
	 * encryption operation generates the tag. For decryption, the input
	 * buffer provides the tag which is consumed resulting in only the
	 * plaintext without a buffer for the tag returned to the caller.
	 */
	if (ctx->enc)
		outlen = used + as;
	else
		outlen = used - as;

	/*
	 * The cipher operation input data is reduced by the associated data
	 * length as this data is processed separately later on.
	 */
	used -= ctx->aead_assoclen;

	/* Allocate cipher request for current operation. */
	areq = sock_kmalloc(sk, areqlen, GFP_KERNEL);
	if (unlikely(!areq))
		return -ENOMEM;
	areq->areqlen = areqlen;
	areq->sk = sk;
	INIT_LIST_HEAD(&areq->rsgl_list);
	areq->tsgl = NULL;
	areq->tsgl_entries = 0;

	/* convert iovecs of output buffers into RX SGL */
	while (outlen > usedpages && msg_data_left(msg)) {
		struct aead_rsgl *rsgl;
		size_t seglen;

		/* limit the amount of readable buffers */
		if (!aead_readable(sk))
			break;

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

		seglen = min_t(size_t, (outlen - usedpages),
			       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)) {
				err = -ENOMEM;
				goto free;
			}
		}

		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)
			goto free;

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

		last_rsgl = rsgl;
		usedpages += err;
		ctx->rcvused += err;
		rsgl->sg_num_bytes = err;
		iov_iter_advance(&msg->msg_iter, err);
	}

	/*
	 * Ensure output buffer is sufficiently large. If the caller provides
	 * less buffer space, only use the relative required input size. This
	 * allows AIO operation where the caller sent all data to be processed
	 * and the AIO operation performs the operation on the different chunks
	 * of the input data.
	 */
	if (usedpages < outlen) {
		size_t less = outlen - usedpages;

		if (used < less) {
			err = -EINVAL;
			goto free;
		}
		used -= less;
		outlen -= less;
	}

	processed = used + ctx->aead_assoclen;
	tsgl = list_first_entry(&ctx->tsgl_list, struct aead_tsgl, list);

	/*
	 * Copy of AAD from source to destination
	 *
	 * The AAD is copied to the destination buffer without change. Even
	 * when user space uses an in-place cipher operation, the kernel
	 * will copy the data as it does not see whether such in-place operation
	 * is initiated.
	 *
	 * To ensure efficiency, the following implementation ensure that the
	 * ciphers are invoked to perform a crypto operation in-place. This
	 * is achieved by memory management specified as follows.
	 */

	/* Use the RX SGL as source (and destination) for crypto op. */
	src = areq->first_rsgl.sgl.sg;

	if (ctx->enc) {
		/*
		 * Encryption operation - The in-place cipher operation is
		 * achieved by the following operation:
		 *
		 * TX SGL: AAD || PT || Tag
		 *	    |	   |
		 *	    | copy |
		 *	    v	   v
		 * RX SGL: AAD || PT
		 */
		err = crypto_aead_copy_sgl(null_tfm, tsgl->sg,
					   areq->first_rsgl.sgl.sg, processed);
		if (err)
			goto free;
		aead_pull_tsgl(sk, processed, NULL, 0);
	} else {
		/*
		 * Decryption operation - To achieve an in-place cipher
		 * operation, the following  SGL structure is used:
		 *
		 * TX SGL: AAD || CT || Tag
		 *	    |	   |	 ^
		 *	    | copy |	 | Create SGL link.
		 *	    v	   v	 |
		 * RX SGL: AAD || CT ----+
		 */

		 /* Copy AAD || CT to RX SGL buffer for in-place operation. */
		err = crypto_aead_copy_sgl(null_tfm, tsgl->sg,
					   areq->first_rsgl.sgl.sg, outlen);
		if (err)
			goto free;

		/* Create TX SGL for tag and chain it to RX SGL. */
		areq->tsgl_entries = aead_count_tsgl(sk, processed,
						     processed - as);
		if (!areq->tsgl_entries)
			areq->tsgl_entries = 1;
		areq->tsgl = sock_kmalloc(sk, sizeof(*areq->tsgl) *
					      areq->tsgl_entries,
					  GFP_KERNEL);
		if (!areq->tsgl) {
			err = -ENOMEM;
			goto free;
		}
		sg_init_table(areq->tsgl, areq->tsgl_entries);

		/* Release TX SGL, except for tag data and reassign tag data. */
		aead_pull_tsgl(sk, processed, areq->tsgl, processed - as);

		/* chain the areq TX SGL holding the tag with RX SGL */
		if (last_rsgl) {
			/* RX SGL present */
			struct af_alg_sgl *sgl_prev = &last_rsgl->sgl;

			sg_unmark_end(sgl_prev->sg + sgl_prev->npages - 1);
			sg_chain(sgl_prev->sg, sgl_prev->npages + 1,
				 areq->tsgl);
		} else
			/* no RX SGL present (e.g. authentication only) */
			src = areq->tsgl;
	}

	/* Initialize the crypto operation */
	aead_request_set_crypt(&areq->aead_req, src,
			       areq->first_rsgl.sgl.sg, used, ctx->iv);
	aead_request_set_ad(&areq->aead_req, ctx->aead_assoclen);
	aead_request_set_tfm(&areq->aead_req, tfm);

	if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
		/* AIO operation */
		areq->iocb = msg->msg_iocb;
		aead_request_set_callback(&areq->aead_req,
					  CRYPTO_TFM_REQ_MAY_BACKLOG,
					  aead_async_cb, areq);
		err = ctx->enc ? crypto_aead_encrypt(&areq->aead_req) :
				 crypto_aead_decrypt(&areq->aead_req);
	} else {
		/* Synchronous operation */
		aead_request_set_callback(&areq->aead_req,
					  CRYPTO_TFM_REQ_MAY_BACKLOG,
					  af_alg_complete, &ctx->completion);
		err = af_alg_wait_for_completion(ctx->enc ?
					 crypto_aead_encrypt(&areq->aead_req) :
					 crypto_aead_decrypt(&areq->aead_req),
					 &ctx->completion);
	}

	/* AIO operation in progress */
	if (err == -EINPROGRESS) {
		sock_hold(sk);

		/* Remember output size that will be generated. */
		areq->outlen = outlen;

		return -EIOCBQUEUED;
	}

free:
	aead_free_areq_sgls(areq);
	if (areq)
		sock_kfree_s(sk, areq, areqlen);

	return err ? err : outlen;
}

static int aead_recvmsg(struct socket *sock, struct msghdr *msg,
			size_t ignored, int flags)
{
	struct sock *sk = sock->sk;
	int ret = 0;

	lock_sock(sk);
	while (msg_data_left(msg)) {
		int err = _aead_recvmsg(sock, msg, ignored, flags);

		/*
		 * This error covers -EIOCBQUEUED which implies that we can
		 * only handle one AIO request. If the caller wants to have
		 * multiple AIO requests in parallel, he must make multiple
		 * separate AIO calls.
		 *
		 * Also return the error if no data has been processed so far.
		 */
		if (err <= 0) {
			if (err == -EIOCBQUEUED || err == -EBADMSG || !ret)
				ret = err;
			goto out;
		}

		ret += err;
	}

out:
	aead_wmem_wakeup(sk);
	release_sock(sk);
	return ret;
}

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

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

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

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

	return mask;
}

static struct proto_ops algif_aead_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	=	aead_sendmsg,
	.sendpage	=	aead_sendpage,
	.recvmsg	=	aead_recvmsg,
	.poll		=	aead_poll,
};

static int aead_check_key(struct socket *sock)
{
	int err = 0;
	struct sock *psk;
	struct alg_sock *pask;
	struct aead_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 aead_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
				  size_t size)
{
	int err;

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

	return aead_sendmsg(sock, msg, size);
}

static ssize_t aead_sendpage_nokey(struct socket *sock, struct page *page,
				       int offset, size_t size, int flags)
{
	int err;

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

	return aead_sendpage(sock, page, offset, size, flags);
}

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

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

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

static struct proto_ops algif_aead_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	=	aead_sendmsg_nokey,
	.sendpage	=	aead_sendpage_nokey,
	.recvmsg	=	aead_recvmsg_nokey,
	.poll		=	aead_poll,
};

static void *aead_bind(const char *name, u32 type, u32 mask)
{
	struct aead_tfm *tfm;
	struct crypto_aead *aead;
	struct crypto_skcipher *null_tfm;

	tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
	if (!tfm)
		return ERR_PTR(-ENOMEM);

	aead = crypto_alloc_aead(name, type, mask);
	if (IS_ERR(aead)) {
		kfree(tfm);
		return ERR_CAST(aead);
	}

	null_tfm = crypto_get_default_null_skcipher2();
	if (IS_ERR(null_tfm)) {
		crypto_free_aead(aead);
		kfree(tfm);
		return ERR_CAST(null_tfm);
	}

	tfm->aead = aead;
	tfm->null_tfm = null_tfm;

	return tfm;
}

static void aead_release(void *private)
{
	struct aead_tfm *tfm = private;

	crypto_free_aead(tfm->aead);
	kfree(tfm);
}

static int aead_setauthsize(void *private, unsigned int authsize)
{
	struct aead_tfm *tfm = private;

	return crypto_aead_setauthsize(tfm->aead, authsize);
}

static int aead_setkey(void *private, const u8 *key, unsigned int keylen)
{
	struct aead_tfm *tfm = private;
	int err;

	err = crypto_aead_setkey(tfm->aead, key, keylen);
	tfm->has_key = !err;

	return err;
}

static void aead_sock_destruct(struct sock *sk)
{
	struct alg_sock *ask = alg_sk(sk);
	struct aead_ctx *ctx = ask->private;
	struct sock *psk = ask->parent;
	struct alg_sock *pask = alg_sk(psk);
	struct aead_tfm *aeadc = pask->private;
	struct crypto_aead *tfm = aeadc->aead;
	unsigned int ivlen = crypto_aead_ivsize(tfm);

	aead_pull_tsgl(sk, ctx->used, NULL, 0);
	crypto_put_default_null_skcipher2();
	sock_kzfree_s(sk, ctx->iv, ivlen);
	sock_kfree_s(sk, ctx, ctx->len);
	af_alg_release_parent(sk);
}

static int aead_accept_parent_nokey(void *private, struct sock *sk)
{
	struct aead_ctx *ctx;
	struct alg_sock *ask = alg_sk(sk);
	struct aead_tfm *tfm = private;
	struct crypto_aead *aead = tfm->aead;
	unsigned int len = sizeof(*ctx);
	unsigned int ivlen = crypto_aead_ivsize(aead);

	ctx = sock_kmalloc(sk, len, GFP_KERNEL);
	if (!ctx)
		return -ENOMEM;
	memset(ctx, 0, len);

	ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL);
	if (!ctx->iv) {
		sock_kfree_s(sk, ctx, len);
		return -ENOMEM;
	}
	memset(ctx->iv, 0, ivlen);

	INIT_LIST_HEAD(&ctx->tsgl_list);
	ctx->len = len;
	ctx->used = 0;
	ctx->rcvused = 0;
	ctx->more = 0;
	ctx->merge = 0;
	ctx->enc = 0;
	ctx->aead_assoclen = 0;
	af_alg_init_completion(&ctx->completion);

	ask->private = ctx;

	sk->sk_destruct = aead_sock_destruct;

	return 0;
}

static int aead_accept_parent(void *private, struct sock *sk)
{
	struct aead_tfm *tfm = private;

	if (!tfm->has_key)
		return -ENOKEY;

	return aead_accept_parent_nokey(private, sk);
}

static const struct af_alg_type algif_type_aead = {
	.bind		=	aead_bind,
	.release	=	aead_release,
	.setkey		=	aead_setkey,
	.setauthsize	=	aead_setauthsize,
	.accept		=	aead_accept_parent,
	.accept_nokey	=	aead_accept_parent_nokey,
	.ops		=	&algif_aead_ops,
	.ops_nokey	=	&algif_aead_ops_nokey,
	.name		=	"aead",
	.owner		=	THIS_MODULE
};

static int __init algif_aead_init(void)
{
	return af_alg_register_type(&algif_type_aead);
}

static void __exit algif_aead_exit(void)
{
	int err = af_alg_unregister_type(&algif_type_aead);
	BUG_ON(err);
}

module_init(algif_aead_init);
module_exit(algif_aead_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");