[PATCH] crypto: af_alg - add async support to algif_aead

[Tadeusz Struk]

Following the async change for algif_skcipher
this patch adds similar async read to algif_aead.

changes in v2:
- change internal data structures from fixed size arrays, limited to
  RSGL_MAX_ENTRIES, to linked list model with no artificial limitation.
- use sock_kmalloc instead of kmalloc for memory allocation
- use sock_hold instead of separate atomic ctr to wait for outstanding request

Signed-off-by: Tadeusz Struk <tadeusz.struk@xxxxxxxxx>
---
 crypto/algif_aead.c |  278 +++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 248 insertions(+), 30 deletions(-)

diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c
index 147069c..3fa1a95 100644
--- a/crypto/algif_aead.c
+++ b/crypto/algif_aead.c
@@ -29,15 +29,24 @@ struct aead_sg_list {
 	struct scatterlist sg[ALG_MAX_PAGES];
 };
 
+struct aead_async_rsgl {
+	struct af_alg_sgl sgl;
+	struct list_head list;
+};
+
+struct aead_async_req {
+	struct scatterlist *tsgl;
+	struct aead_async_rsgl first_rsgl;
+	struct list_head list;
+	struct kiocb *iocb;
+	unsigned int tsgls;
+	char iv[];
+};
+
 struct aead_ctx {
 	struct aead_sg_list tsgl;
-	/*
-	 * RSGL_MAX_ENTRIES is an artificial limit where user space at maximum
-	 * can cause the kernel to allocate RSGL_MAX_ENTRIES * ALG_MAX_PAGES
-	 * pages
-	 */
-#define RSGL_MAX_ENTRIES ALG_MAX_PAGES
-	struct af_alg_sgl rsgl[RSGL_MAX_ENTRIES];
+	struct aead_async_rsgl first_rsgl;
+	struct list_head list;
 
 	void *iv;
 
@@ -75,6 +84,17 @@ static inline bool aead_sufficient_data(struct aead_ctx *ctx)
 	return ctx->used >= ctx->aead_assoclen + as;
 }
 
+static void aead_reset_ctx(struct aead_ctx *ctx)
+{
+	struct aead_sg_list *sgl = &ctx->tsgl;
+
+	sg_init_table(sgl->sg, ALG_MAX_PAGES);
+	sgl->cur = 0;
+	ctx->used = 0;
+	ctx->more = 0;
+	ctx->merge = 0;
+}
+
 static void aead_put_sgl(struct sock *sk)
 {
 	struct alg_sock *ask = alg_sk(sk);
@@ -90,11 +110,6 @@ static void aead_put_sgl(struct sock *sk)
 		put_page(sg_page(sg + i));
 		sg_assign_page(sg + i, NULL);
 	}
-	sg_init_table(sg, ALG_MAX_PAGES);
-	sgl->cur = 0;
-	ctx->used = 0;
-	ctx->more = 0;
-	ctx->merge = 0;
 }
 
 static void aead_wmem_wakeup(struct sock *sk)
@@ -240,6 +255,7 @@ static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 		if (!aead_writable(sk)) {
 			/* user space sent too much data */
 			aead_put_sgl(sk);
+			aead_reset_ctx(ctx);
 			err = -EMSGSIZE;
 			goto unlock;
 		}
@@ -251,6 +267,7 @@ static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 
 			if (sgl->cur >= ALG_MAX_PAGES) {
 				aead_put_sgl(sk);
+				aead_reset_ctx(ctx);
 				err = -E2BIG;
 				goto unlock;
 			}
@@ -287,6 +304,7 @@ static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	ctx->more = msg->msg_flags & MSG_MORE;
 	if (!ctx->more && !aead_sufficient_data(ctx)) {
 		aead_put_sgl(sk);
+		aead_reset_ctx(ctx);
 		err = -EMSGSIZE;
 	}
 
@@ -322,6 +340,7 @@ static ssize_t aead_sendpage(struct socket *sock, struct page *page,
 	if (!aead_writable(sk)) {
 		/* user space sent too much data */
 		aead_put_sgl(sk);
+		aead_reset_ctx(ctx);
 		err = -EMSGSIZE;
 		goto unlock;
 	}
@@ -339,6 +358,7 @@ done:
 	ctx->more = flags & MSG_MORE;
 	if (!ctx->more && !aead_sufficient_data(ctx)) {
 		aead_put_sgl(sk);
+		aead_reset_ctx(ctx);
 		err = -EMSGSIZE;
 	}
 
@@ -349,23 +369,189 @@ unlock:
 	return err ?: size;
 }
 
-static int aead_recvmsg(struct socket *sock, struct msghdr *msg, size_t ignored, int flags)
+#define GET_ASYM_REQ(req, tfm) (struct aead_async_req *) \
+		((char *)req + sizeof(struct aead_request) + \
+		 crypto_aead_reqsize(tfm))
+
+ #define GET_REQ_SIZE(tfm) sizeof(struct aead_async_req) + \
+	crypto_aead_reqsize(tfm) + crypto_aead_ivsize(tfm) + \
+	sizeof(struct aead_request)
+
+static void aead_async_cb(struct crypto_async_request *_req, int err)
+{
+	struct sock *sk = _req->data;
+	struct alg_sock *ask = alg_sk(sk);
+	struct aead_ctx *ctx = ask->private;
+	struct crypto_aead *tfm = crypto_aead_reqtfm(&ctx->aead_req);
+	struct aead_request *req = aead_request_cast(_req);
+	struct aead_async_req *areq = GET_ASYM_REQ(req, tfm);
+	struct scatterlist *sg = areq->tsgl;
+	struct aead_async_rsgl *rsgl;
+	struct kiocb *iocb = areq->iocb;
+	unsigned int i, reqlen = GET_REQ_SIZE(tfm);
+
+	list_for_each_entry(rsgl, &areq->list, list) {
+		af_alg_free_sg(&rsgl->sgl);
+		if (rsgl != &areq->first_rsgl)
+			sock_kfree_s(sk, rsgl, sizeof(*rsgl));
+	}
+
+	for (i = 0; i < areq->tsgls; i++)
+		put_page(sg_page(sg + i));
+
+	sock_kfree_s(sk, areq->tsgl, sizeof(*areq->tsgl) * areq->tsgls);
+	sock_kfree_s(sk, req, reqlen);
+	__sock_put(sk);
+	iocb->ki_complete(iocb, err, err);
+}
+
+static int aead_recvmsg_async(struct socket *sock, struct msghdr *msg,
+			      int flags)
+{
+	struct sock *sk = sock->sk;
+	struct alg_sock *ask = alg_sk(sk);
+	struct aead_ctx *ctx = ask->private;
+	struct crypto_aead *tfm = crypto_aead_reqtfm(&ctx->aead_req);
+	struct aead_async_req *areq;
+	struct aead_request *req = NULL;
+	struct aead_sg_list *sgl = &ctx->tsgl;
+	struct aead_async_rsgl *last_rsgl = NULL, *rsgl;
+	unsigned int as = crypto_aead_authsize(tfm);
+	unsigned int i, reqlen = GET_REQ_SIZE(tfm);
+	int err = -ENOMEM;
+	unsigned long used;
+	size_t outlen;
+	size_t usedpages = 0;
+
+	lock_sock(sk);
+	if (ctx->more) {
+		err = aead_wait_for_data(sk, flags);
+		if (err)
+			goto unlock;
+	}
+
+	used = ctx->used;
+	outlen = used;
+
+	if (!aead_sufficient_data(ctx))
+		goto unlock;
+
+	req = sock_kmalloc(sk, reqlen, GFP_KERNEL);
+	if (unlikely(!req))
+		goto unlock;
+
+	areq = GET_ASYM_REQ(req, tfm);
+	memset(&areq->first_rsgl, '\0', sizeof(areq->first_rsgl));
+	INIT_LIST_HEAD(&areq->list);
+	areq->iocb = msg->msg_iocb;
+	memcpy(areq->iv, ctx->iv, crypto_aead_ivsize(tfm));
+	aead_request_set_tfm(req, tfm);
+	aead_request_set_ad(req, ctx->aead_assoclen);
+	aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+				  aead_async_cb, sk);
+	used -= ctx->aead_assoclen + (ctx->enc ? as : 0);
+
+	/* take over all tx sgls from ctx */
+	areq->tsgl = sock_kmalloc(sk, sizeof(*areq->tsgl) * sgl->cur,
+				  GFP_KERNEL);
+	if (unlikely(!areq->tsgl))
+		goto free;
+
+	sg_init_table(areq->tsgl, sgl->cur);
+	for (i = 0; i < sgl->cur; i++)
+		sg_set_page(&areq->tsgl[i], sg_page(&sgl->sg[i]),
+			    sgl->sg[i].length, sgl->sg[i].offset);
+
+	areq->tsgls = sgl->cur;
+
+	/* create rx sgls */
+	while (iov_iter_count(&msg->msg_iter)) {
+		size_t seglen = min_t(size_t, iov_iter_count(&msg->msg_iter),
+				      (outlen - usedpages));
+
+		if (list_empty(&areq->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->list);
+
+		/* make one iovec available as scatterlist */
+		err = af_alg_make_sg(&rsgl->sgl, &msg->msg_iter, seglen);
+		if (err < 0)
+			goto free;
+
+		usedpages += err;
+
+		/* chain the new scatterlist with previous one */
+		if (last_rsgl)
+			af_alg_link_sg(&last_rsgl->sgl, &rsgl->sgl);
+
+		last_rsgl = rsgl;
+
+		/* we do not need more iovecs as we have sufficient memory */
+		if (outlen <= usedpages)
+			break;
+
+		iov_iter_advance(&msg->msg_iter, err);
+	}
+	err = -EINVAL;
+	/* ensure output buffer is sufficiently large */
+	if (usedpages < outlen)
+		goto free;
+
+	aead_request_set_crypt(req, areq->tsgl, areq->first_rsgl.sgl.sg, used,
+			       areq->iv);
+	err = ctx->enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req);
+	if (err) {
+		if (err == -EINPROGRESS) {
+			sock_hold(sk);
+			err = -EIOCBQUEUED;
+			aead_reset_ctx(ctx);
+			goto unlock;
+		} else if (err == -EBADMSG) {
+			aead_put_sgl(sk);
+			aead_reset_ctx(ctx);
+		}
+		goto free;
+	}
+	aead_put_sgl(sk);
+	aead_reset_ctx(ctx);
+
+free:
+	list_for_each_entry(rsgl, &areq->list, list) {
+		af_alg_free_sg(&rsgl->sgl);
+		if (rsgl != &areq->first_rsgl)
+			sock_kfree_s(sk, rsgl, sizeof(*rsgl));
+	}
+	if (areq->tsgl)
+		sock_kfree_s(sk, areq->tsgl, sizeof(*areq->tsgl) * areq->tsgls);
+	if (req)
+		sock_kfree_s(sk, req, reqlen);
+unlock:
+	aead_wmem_wakeup(sk);
+	release_sock(sk);
+	return err ? err : outlen;
+}
+
+static int aead_recvmsg_sync(struct socket *sock, struct msghdr *msg, int flags)
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct aead_ctx *ctx = ask->private;
 	unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
 	struct aead_sg_list *sgl = &ctx->tsgl;
-	unsigned int i = 0;
+	struct aead_async_rsgl *last_rsgl = NULL;
+	struct aead_async_rsgl *rsgl, *tmp;
 	int err = -EINVAL;
 	unsigned long used = 0;
 	size_t outlen = 0;
 	size_t usedpages = 0;
-	unsigned int cnt = 0;
-
-	/* Limit number of IOV blocks to be accessed below */
-	if (msg->msg_iter.nr_segs > RSGL_MAX_ENTRIES)
-		return -ENOMSG;
 
 	lock_sock(sk);
 
@@ -417,21 +603,33 @@ static int aead_recvmsg(struct socket *sock, struct msghdr *msg, size_t ignored,
 		size_t seglen = min_t(size_t, iov_iter_count(&msg->msg_iter),
 				      (outlen - usedpages));
 
+		if (list_empty(&ctx->list))
+			rsgl = &ctx->first_rsgl;
+		else {
+			rsgl = sock_kmalloc(sk, sizeof(*rsgl), GFP_KERNEL);
+			if (unlikely(!rsgl)) {
+				err = -ENOMEM;
+				goto unlock;
+			}
+		}
+		rsgl->sgl.npages = 0;
+		list_add_tail(&rsgl->list, &ctx->list);
+
 		/* make one iovec available as scatterlist */
-		err = af_alg_make_sg(&ctx->rsgl[cnt], &msg->msg_iter,
-				     seglen);
+		err = af_alg_make_sg(&rsgl->sgl, &msg->msg_iter, seglen);
 		if (err < 0)
 			goto unlock;
 		usedpages += err;
 		/* chain the new scatterlist with previous one */
-		if (cnt)
-			af_alg_link_sg(&ctx->rsgl[cnt-1], &ctx->rsgl[cnt]);
+		if (last_rsgl)
+			af_alg_link_sg(&last_rsgl->sgl, &rsgl->sgl);
+
+		last_rsgl = rsgl;
 
 		/* we do not need more iovecs as we have sufficient memory */
 		if (outlen <= usedpages)
 			break;
 		iov_iter_advance(&msg->msg_iter, err);
-		cnt++;
 	}
 
 	err = -EINVAL;
@@ -440,8 +638,7 @@ static int aead_recvmsg(struct socket *sock, struct msghdr *msg, size_t ignored,
 		goto unlock;
 
 	sg_mark_end(sgl->sg + sgl->cur - 1);
-
-	aead_request_set_crypt(&ctx->aead_req, sgl->sg, ctx->rsgl[0].sg,
+	aead_request_set_crypt(&ctx->aead_req, sgl->sg, ctx->first_rsgl.sgl.sg,
 			       used, ctx->iv);
 	aead_request_set_ad(&ctx->aead_req, ctx->aead_assoclen);
 
@@ -452,25 +649,40 @@ static int aead_recvmsg(struct socket *sock, struct msghdr *msg, size_t ignored,
 
 	if (err) {
 		/* EBADMSG implies a valid cipher operation took place */
-		if (err == -EBADMSG)
+		if (err == -EBADMSG) {
 			aead_put_sgl(sk);
+			aead_reset_ctx(ctx);
+		}
 		goto unlock;
 	}
 
 	aead_put_sgl(sk);
+	aead_reset_ctx(ctx);
 
 	err = 0;
 
 unlock:
-	for (i = 0; i < cnt; i++)
-		af_alg_free_sg(&ctx->rsgl[i]);
-
+	list_for_each_entry_safe(rsgl, tmp, &ctx->list, list) {
+		af_alg_free_sg(&rsgl->sgl);
+		if (rsgl != &ctx->first_rsgl)
+			sock_kfree_s(sk, rsgl, sizeof(*rsgl));
+		list_del(&rsgl->list);
+	}
+	INIT_LIST_HEAD(&ctx->list);
 	aead_wmem_wakeup(sk);
 	release_sock(sk);
 
 	return err ? err : outlen;
 }
 
+static int aead_recvmsg(struct socket *sock, struct msghdr *msg, size_t ignored,
+			int flags)
+{
+	return (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) ?
+		aead_recvmsg_async(sock, msg, flags) :
+		aead_recvmsg_sync(sock, msg, flags);
+}
+
 static unsigned int aead_poll(struct file *file, struct socket *sock,
 			      poll_table *wait)
 {
@@ -539,7 +751,12 @@ static void aead_sock_destruct(struct sock *sk)
 	struct aead_ctx *ctx = ask->private;
 	unsigned int ivlen = crypto_aead_ivsize(
 				crypto_aead_reqtfm(&ctx->aead_req));
+	int ctr = 0;
+
+	while (atomic_read(&sk->sk_refcnt) != 0 && ctr++ < 10)
+		msleep(100);
 
+	WARN_ON(atomic_read(&sk->sk_refcnt) != 0);
 	aead_put_sgl(sk);
 	sock_kzfree_s(sk, ctx->iv, ivlen);
 	sock_kfree_s(sk, ctx, ctx->len);
@@ -574,6 +791,7 @@ static int aead_accept_parent(void *private, struct sock *sk)
 	ctx->aead_assoclen = 0;
 	af_alg_init_completion(&ctx->completion);
 	sg_init_table(ctx->tsgl.sg, ALG_MAX_PAGES);
+	INIT_LIST_HEAD(&ctx->list);
 
 	ask->private = ctx;