[PATCH v3 0/2] crypto: AF_ALG memory management fix

[PATCH v3 0/2] crypto: AF_ALG memory management fix

[Stephan Müller]

Hi Herbert,

Changes v3:
* in *_pull_tsgl: make sure ctx->processed cannot be less than zero
* perform fuzzing of all input parameters with bogus values

Changes v2:
* import fix from Harsh Jain <harsh@chelsio.com> to remove SG
  from list before freeing
* fix return code used for ki_complete to match AIO behavior
  with sync behavior
* rename variable list -> tsgl_list
* update the algif_aead patch to include a dynamic TX SGL
  allocation similar to what algif_skcipher does. This allows
  concurrent continuous read/write operations to the extent
  you requested. Although I have not implemented "pairs of
  TX/RX SGLs" as I think that is even more overhead, the
  implementation conceptually defines such pairs. The recvmsg
  call defines how much from the input data is processed.
  The caller can have arbitrary number of sendmsg calls
  where the data is added to the TX SGL before an recvmsg
  asks the kernel to process a given amount (or all) of the
  TX SGL.

With the changes, you will see a lot of code duplication now
as I deliberately tried to use the same struct and variable names,
the same function names and even the same oder of functions.
If you agree to this patch, I volunteer to provide a followup
patch that will extract the code duplication into common
functions.

Please find attached memory management updates to

- simplify the code: the old AIO memory management is very
  complex and seemingly very fragile -- the update now
  eliminates all reported bugs in the skcipher and AEAD
  interfaces which allowed the kernel to be crashed by
  an unprivileged user

- streamline the code: there is one code path for AIO and sync
  operation; the code between algif_skcipher and algif_aead
  is very similar (if that patch set is accepted, I volunteer
  to reduce code duplication by moving service operations
  into af_alg.c and to further unify the TX SGL handling)

- unify the AIO and sync operation which only differ in the
  kernel crypto API callback and whether to wait for the
  crypto operation or not

- fix all reported bugs regarding the handling of multiple
  IOCBs.

The following testing was performed:

- stress testing to verify that no memleaks exist

- testing using Tadeusz Struck AIO test tool (see
  https://github.com/tstruk/afalg_async_test) -- the AEAD test
  is not applicable any more due to the changed user space
  interface; the skcipher test works once the user space
  interface change is honored in the test code

- using the libkcapi test suite, all tests including the
  originally failing ones (AIO with multiple IOCBs) work now --
  the current libkcapi code artificially limits the AEAD
  operation to one IOCB. After altering the libkcapi code
  to allow multiple IOCBs, the testing works flawless.

Stephan Mueller (2):
  crypto: skcipher AF_ALG - overhaul memory management
  crypto: aead AF_ALG - overhaul memory management

 crypto/algif_aead.c     | 673 +++++++++++++++++++++++++-----------------------
 crypto/algif_skcipher.c | 477 ++++++++++++++--------------------
 2 files changed, 554 insertions(+), 596 deletions(-)

-- 
2.9.3

[PATCH v3 1/2] crypto: skcipher AF_ALG - overhaul memory management

[Stephan Müller]

The updated memory management is described in the top part of the code.
As one benefit of the changed memory management, the AIO and synchronous
operation is now implemented in one common function. The AF_ALG
operation uses the async kernel crypto API interface for each cipher
operation. Thus, the only difference between the AIO and sync operation
types visible from user space is:

1. the callback function to be invoked when the asynchronous operation
   is completed

2. whether to wait for the completion of the kernel crypto API operation
   or not

In addition, the code structure is adjusted to match the structure of
algif_aead for easier code assessment.

The user space interface changed slightly as follows: the old AIO
operation returned zero upon success and < 0 in case of an error to user
space. As all other AF_ALG interfaces (including the sync skcipher
interface) returned the number of processed bytes upon success and < 0
in case of an error, the new skcipher interface (regardless of AIO or
sync) returns the number of processed bytes in case of success.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
 crypto/algif_skcipher.c | 477 ++++++++++++++++++++----------------------------
 1 file changed, 198 insertions(+), 279 deletions(-)

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index a9e79d8..d873de2 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -10,6 +10,25 @@
  * 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. To support multiple recvmsg operations operating
+ * on one TX SGL, an offset pointer into the TX SGL is maintained. The TX SGL
+ * that is used for the crypto request is scatterwalk_ffwd by the offset
+ * pointer to obtain the start address the crypto operation shall use for
+ * the input data.
+ *
+ * After the completion of the crypto operation, the RX SGL and the cipher
+ * request is released. The processed TX SGL parts are released together with
+ * the RX SGL release and the offset pointer is reduced by the released
+ * data.
  */
 
 #include <crypto/scatterwalk.h>
@@ -31,78 +50,50 @@ struct skcipher_sg_list {
 	struct scatterlist sg[0];
 };
 
+struct skcipher_rsgl {
+	struct af_alg_sgl sgl;
+	struct list_head list;
+};
+
+struct skcipher_async_req {
+	struct kiocb *iocb;
+	struct sock *sk;
+
+	struct skcipher_rsgl first_sgl;
+	struct list_head rsgl_list;
+
+	unsigned int areqlen;
+	struct skcipher_request req;
+};
+
 struct skcipher_tfm {
 	struct crypto_skcipher *skcipher;
 	bool has_key;
 };
 
 struct skcipher_ctx {
-	struct list_head tsgl;
-	struct af_alg_sgl rsgl;
+	struct list_head tsgl_list;
 
 	void *iv;
 
 	struct af_alg_completion completion;
 
-	atomic_t inflight;
+	unsigned int inflight;
 	size_t used;
+	size_t processed;
 
-	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;
+	unsigned int len;
 };
 
-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;
-};
+static DECLARE_WAIT_QUEUE_HEAD(skcipher_aio_finish_wait);
 
 #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);
@@ -117,15 +108,15 @@ static inline bool skcipher_writable(struct sock *sk)
 	return PAGE_SIZE <= skcipher_sndbuf(sk);
 }
 
-static int skcipher_alloc_sgl(struct sock *sk)
+static int skcipher_alloc_tsgl(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))
+	sgl = list_entry(ctx->tsgl_list.prev, struct skcipher_sg_list, list);
+	if (!list_empty(&ctx->tsgl_list))
 		sg = sgl->sg;
 
 	if (!sg || sgl->cur >= MAX_SGL_ENTS) {
@@ -141,13 +132,13 @@ static int skcipher_alloc_sgl(struct sock *sk)
 		if (sg)
 			sg_chain(sg, MAX_SGL_ENTS + 1, sgl->sg);
 
-		list_add_tail(&sgl->list, &ctx->tsgl);
+		list_add_tail(&sgl->list, &ctx->tsgl_list);
 	}
 
 	return 0;
 }
 
-static void skcipher_pull_sgl(struct sock *sk, size_t used, int put)
+static void skcipher_pull_tsgl(struct sock *sk, size_t used)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
@@ -155,8 +146,8 @@ static void skcipher_pull_sgl(struct sock *sk, size_t used, int put)
 	struct scatterlist *sg;
 	int i;
 
-	while (!list_empty(&ctx->tsgl)) {
-		sgl = list_first_entry(&ctx->tsgl, struct skcipher_sg_list,
+	while (!list_empty(&ctx->tsgl_list)) {
+		sgl = list_first_entry(&ctx->tsgl_list, struct skcipher_sg_list,
 				       list);
 		sg = sgl->sg;
 
@@ -172,29 +163,39 @@ static void skcipher_pull_sgl(struct sock *sk, size_t used, int put)
 			used -= plen;
 			ctx->used -= plen;
 
+			/* in case of error, pull data that is not processed */
+			if (ctx->processed < plen)
+				ctx->processed = 0;
+			else
+				ctx->processed -= plen;
+
 			if (sg[i].length)
 				return;
-			if (put)
-				put_page(sg_page(sg + i));
+
+			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));
+		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)
+static void skcipher_free_rsgl(struct skcipher_async_req *areq)
 {
-	struct alg_sock *ask = alg_sk(sk);
-	struct skcipher_ctx *ctx = ask->private;
+	struct sock *sk = areq->sk;
+	struct skcipher_rsgl *rsgl, *tmp;
 
-	skcipher_pull_sgl(sk, ctx->used, 1);
+	list_for_each_entry_safe(rsgl, tmp, &areq->rsgl_list, list) {
+		af_alg_free_sg(&rsgl->sgl);
+		list_del(&rsgl->list);
+		if (rsgl != &areq->first_sgl)
+			sock_kfree_s(sk, rsgl, sizeof(*rsgl));
+	}
 }
 
 static int skcipher_wait_for_wmem(struct sock *sk, unsigned flags)
@@ -348,7 +349,7 @@ static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg,
 		size_t plen;
 
 		if (ctx->merge) {
-			sgl = list_entry(ctx->tsgl.prev,
+			sgl = list_entry(ctx->tsgl_list.prev,
 					 struct skcipher_sg_list, list);
 			sg = sgl->sg + sgl->cur - 1;
 			len = min_t(unsigned long, len,
@@ -378,11 +379,12 @@ static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg,
 
 		len = min_t(unsigned long, len, skcipher_sndbuf(sk));
 
-		err = skcipher_alloc_sgl(sk);
+		err = skcipher_alloc_tsgl(sk);
 		if (err)
 			goto unlock;
 
-		sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
+		sgl = list_entry(ctx->tsgl_list.prev, struct skcipher_sg_list,
+				 list);
 		sg = sgl->sg;
 		if (sgl->cur)
 			sg_unmark_end(sg + sgl->cur - 1);
@@ -453,12 +455,12 @@ static ssize_t skcipher_sendpage(struct socket *sock, struct page *page,
 			goto unlock;
 	}
 
-	err = skcipher_alloc_sgl(sk);
+	err = skcipher_alloc_tsgl(sk);
 	if (err)
 		goto unlock;
 
 	ctx->merge = 0;
-	sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
+	sgl = list_entry(ctx->tsgl_list.prev, struct skcipher_sg_list, list);
 
 	if (sgl->cur)
 		sg_unmark_end(sgl->sg + sgl->cur - 1);
@@ -479,25 +481,37 @@ static ssize_t skcipher_sendpage(struct socket *sock, struct page *page,
 	return err ?: size;
 }
 
-static int skcipher_all_sg_nents(struct skcipher_ctx *ctx)
+static void skcipher_async_cb(struct crypto_async_request *req, int err)
 {
-	struct skcipher_sg_list *sgl;
-	struct scatterlist *sg;
-	int nents = 0;
+	struct skcipher_async_req *areq = req->data;
+	struct sock *sk = areq->sk;
+	struct alg_sock *ask = alg_sk(sk);
+	struct skcipher_ctx *ctx = ask->private;
+	struct kiocb *iocb = areq->iocb;
+	unsigned int resultlen;
 
-	list_for_each_entry(sgl, &ctx->tsgl, list) {
-		sg = sgl->sg;
+	lock_sock(sk);
 
-		while (!sg->length)
-			sg++;
+	BUG_ON(!ctx->inflight);
 
-		nents += sg_nents(sg);
-	}
-	return nents;
+	/* Buffer size written by crypto operation. */
+	resultlen = areq->req.cryptlen;
+
+	skcipher_free_rsgl(areq);
+	skcipher_pull_tsgl(sk, areq->req.cryptlen);
+	sock_kfree_s(sk, areq, areq->areqlen);
+	__sock_put(sk);
+	ctx->inflight--;
+
+	iocb->ki_complete(iocb, err ? err : resultlen, 0);
+
+	release_sock(sk);
+
+	wake_up_interruptible(&skcipher_aio_finish_wait);
 }
 
-static int skcipher_recvmsg_async(struct socket *sock, struct msghdr *msg,
-				  int flags)
+static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
+			    size_t ignored, int flags)
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
@@ -506,215 +520,131 @@ static int skcipher_recvmsg_async(struct socket *sock, struct msghdr *msg,
 	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);
+	unsigned int bs = crypto_skcipher_blocksize(tfm);
+	unsigned int areqlen = sizeof(struct skcipher_async_req) +
+			       crypto_skcipher_reqsize(tfm);
+	struct skcipher_sg_list *tsgl;
+	struct skcipher_async_req *areq;
+	struct skcipher_rsgl *last_rsgl = NULL;
+	struct scatterlist tsgl_head[2], *tsgl_head_p;
 	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;
+	size_t len = 0;
 
 	lock_sock(sk);
-	tx_nents = skcipher_all_sg_nents(ctx);
-	sreq->tsg = kcalloc(tx_nents, sizeof(*sg), GFP_KERNEL);
-	if (unlikely(!sreq->tsg))
+
+	/* Allocate cipher request for current operation. */
+	areq = sock_kmalloc(sk, areqlen, GFP_KERNEL);
+	if (unlikely(!areq))
 		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);
+	areq->areqlen = areqlen;
+	areq->sk = sk;
+	INIT_LIST_HEAD(&areq->rsgl_list);
 
-	while (iov_iter_count(&msg->msg_iter)) {
-		struct skcipher_async_rsgl *rsgl;
-		int used;
+	/* convert iovecs of output buffers into RX SGL */
+	while (len < ctx->used && iov_iter_count(&msg->msg_iter)) {
+		struct skcipher_rsgl *rsgl;
+		size_t seglen;
 
 		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;
-			}
+		seglen = min_t(size_t, ctx->used,
+			       iov_iter_count(&msg->msg_iter));
 
-			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);
+		if (list_empty(&areq->rsgl_list)) {
+			rsgl = &areq->first_sgl;
 		} else {
-			rsgl = kmalloc(sizeof(*rsgl), GFP_KERNEL);
+			rsgl = sock_kmalloc(sk, 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)
+		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;
-		len += used;
-		skcipher_pull_sgl(sk, used, 0);
-		iov_iter_advance(&msg->msg_iter, used);
+		len += err;
+		iov_iter_advance(&msg->msg_iter, err);
 	}
 
-	if (mark)
-		sg_mark_end(sreq->tsg + txbufs - 1);
+	/* Process only as much RX buffers for which we have TX data */
+	if (len > ctx->used)
+		len = ctx->used;
+
+	/*
+	 * If more buffers are to be expected to be processed, process only
+	 * full block size buffers.
+	 */
+	if (ctx->more || len < ctx->used)
+		len -= len % bs;
+
+	tsgl = list_first_entry(&ctx->tsgl_list, struct skcipher_sg_list, list);
+	/* Get the head of the SGL we want to process */
+	tsgl_head_p = scatterwalk_ffwd(tsgl_head, tsgl->sg, ctx->processed);
+	BUG_ON(!tsgl_head_p);
+
+	/* Initialize the crypto operation */
+	skcipher_request_set_tfm(&areq->req, tfm);
+	skcipher_request_set_crypt(&areq->req, tsgl_head_p,
+				   areq->first_sgl.sgl.sg, len, ctx->iv);
+
+	if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
+		/* AIO operation */
+		areq->iocb = msg->msg_iocb;
+		skcipher_request_set_callback(&areq->req,
+					      CRYPTO_TFM_REQ_MAY_SLEEP,
+					      skcipher_async_cb, areq);
+		err = ctx->enc ? crypto_skcipher_encrypt(&areq->req) :
+				 crypto_skcipher_decrypt(&areq->req);
+	} else {
+		/* Synchronous operation */
+		skcipher_request_set_callback(&areq->req,
+					      CRYPTO_TFM_REQ_MAY_SLEEP |
+					      CRYPTO_TFM_REQ_MAY_BACKLOG,
+					      af_alg_complete,
+					      &ctx->completion);
+		err = af_alg_wait_for_completion(ctx->enc ?
+					crypto_skcipher_encrypt(&areq->req) :
+					crypto_skcipher_decrypt(&areq->req),
+						 &ctx->completion);
+	}
 
-	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);
+	/* AIO operation in progress */
 	if (err == -EINPROGRESS) {
-		atomic_inc(&ctx->inflight);
+		sock_hold(sk);
 		err = -EIOCBQUEUED;
-		sreq = NULL;
+		ctx->inflight++;
+		/* Remember the TX bytes that were processed. */
+		ctx->processed += len;
 		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);
+	} else if (!err)
+		/* Remember the TX bytes that were processed. */
+		ctx->processed += len;
 
 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;
+	skcipher_free_rsgl(areq);
+	if (areq)
+		sock_kfree_s(sk, areq, areqlen);
+	skcipher_pull_tsgl(sk, len);
 
 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);
+	return err ? err : len;
 }
 
 static unsigned int skcipher_poll(struct file *file, struct socket *sock,
@@ -723,10 +653,9 @@ static unsigned int skcipher_poll(struct file *file, struct socket *sock,
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct skcipher_ctx *ctx = ask->private;
-	unsigned int mask;
+	unsigned int mask = 0;
 
 	sock_poll_wait(file, sk_sleep(sk), wait);
-	mask = 0;
 
 	if (ctx->used)
 		mask |= POLLIN | POLLRDNORM;
@@ -894,26 +823,20 @@ static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
 	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);
+	struct sock *psk = ask->parent;
+	struct alg_sock *pask = alg_sk(psk);
+	struct skcipher_tfm *skc = pask->private;
+	struct crypto_skcipher *tfm = skc->skcipher;
 
-	if (atomic_read(&ctx->inflight))
-		skcipher_wait(sk);
+	/* Suspend caller if AIO operations are in flight. */
+	wait_event_interruptible(skcipher_aio_finish_wait,
+				 (ctx->inflight == 0));
 
-	skcipher_free_sgl(sk);
+	skcipher_pull_tsgl(sk, ctx->used);
 	sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
 	sock_kfree_s(sk, ctx, ctx->len);
 	af_alg_release_parent(sk);
@@ -925,7 +848,7 @@ static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
 	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);
+	unsigned int len = sizeof(*ctx);
 
 	ctx = sock_kmalloc(sk, len, GFP_KERNEL);
 	if (!ctx)
@@ -940,22 +863,18 @@ static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
 
 	memset(ctx->iv, 0, crypto_skcipher_ivsize(skcipher));
 
-	INIT_LIST_HEAD(&ctx->tsgl);
+	INIT_LIST_HEAD(&ctx->tsgl_list);
 	ctx->len = len;
 	ctx->used = 0;
+	ctx->processed = 0;
+	ctx->inflight = 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;
-- 
2.9.3

[PATCH v3 2/2] crypto: aead AF_ALG - overhaul memory management

[Stephan Müller]

The updated memory management is described in the top part of the code.
As one benefit of the changed memory management, the AIO and synchronous
operation is now implemented in one common function. The AF_ALG
operation uses the async kernel crypto API interface for each cipher
operation. Thus, the only difference between the AIO and sync operation
types visible from user space is:

1. the callback function to be invoked when the asynchronous operation
   is completed

2. whether to wait for the completion of the kernel crypto API operation
   or not

The change includes the overhaul of the TX and RX SGL handling. The TX
SGL holding the data sent from user space to the kernel is now dynamic
similar to algif_skcipher. This dynamic nature allows a continuous
operation of a thread sending data and a second thread receiving the
data. These threads do not need to synchronize as the kernel processes
as much data from the TX SGL to fill the RX SGL.

The caller reading the data from the kernel defines the amount of data
to be processed. Considering that the interface covers AEAD
authenticating ciphers, the reader must provide the buffer in the
correct size. Thus the reader defines the encryption size.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
 crypto/algif_aead.c | 673 +++++++++++++++++++++++++++-------------------------
 1 file changed, 356 insertions(+), 317 deletions(-)

diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c
index 533265f..ed49fce 100644
--- a/crypto/algif_aead.c
+++ b/crypto/algif_aead.c
@@ -11,6 +11,26 @@
  * 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. To support multiple recvmsg operations operating
+ * on one TX SGL, an offset pointer into the TX SGL is maintained. The TX SGL
+ * that is used for the crypto request is scatterwalk_ffwd by the offset
+ * pointer to obtain the start address the crypto operation shall use for
+ * the input data.
+ *
+ * After the completion of the crypto operation, the RX SGL and the cipher
+ * request is released. The processed TX SGL parts are released together with
+ * the RX SGL release and the offset pointer is reduced by the released
+ * data.
  */
 
 #include <crypto/internal/aead.h>
@@ -24,45 +44,55 @@
 #include <linux/net.h>
 #include <net/sock.h>
 
-struct aead_sg_list {
-	unsigned int cur;
-	struct scatterlist sg[ALG_MAX_PAGES];
+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_async_rsgl {
+struct aead_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 sock *sk;
+
+	struct aead_rsgl first_rsgl;	/* First RX SG */
+	struct list_head rsgl_list;	/* Track RX SGs */
+
+	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_ctx {
-	struct aead_sg_list tsgl;
-	struct aead_async_rsgl first_rsgl;
-	struct list_head list;
+	struct list_head tsgl_list;	/* Link to TX SGL */
 
 	void *iv;
+	size_t aead_assoclen;
 
-	struct af_alg_completion completion;
+	struct af_alg_completion completion;	/* sync work queue */
 
-	unsigned long used;
+	unsigned int inflight;	/* Outstanding AIO ops */
+	size_t used;		/* TX bytes sent to kernel */
+	size_t processed;	/* Processed TX bytes */
 
-	unsigned int len;
-	bool more;
-	bool merge;
-	bool enc;
+	bool more;		/* More data to be expected? */
+	bool merge;		/* Merge new data into existing SG */
+	bool enc;		/* Crypto operation: enc, dec */
 
-	size_t aead_assoclen;
-	struct aead_request aead_req;
+	unsigned int len;	/* Length of allocated memory for this struct */
+	struct crypto_aead *aead_tfm;
 };
 
+static DECLARE_WAIT_QUEUE_HEAD(aead_aio_finish_wait);
+
+#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);
@@ -79,42 +109,133 @@ static inline bool aead_writable(struct sock *sk)
 
 static inline bool aead_sufficient_data(struct aead_ctx *ctx)
 {
-	unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
+	unsigned int as = crypto_aead_authsize(ctx->aead_tfm);
 
 	/*
 	 * The minimum amount of memory needed for an AEAD cipher is
 	 * the AAD and in case of decryption the tag.
+	 *
+	 * Also, sufficient data must be available after disregarding the
+	 * already processed data.
 	 */
-	return ctx->used >= ctx->aead_assoclen + (ctx->enc ? 0 : as);
+	return ctx->used >= ctx->aead_assoclen + (ctx->enc ? 0 : as) +
+			    ctx->processed;
 }
 
-static void aead_reset_ctx(struct aead_ctx *ctx)
+static int aead_alloc_tsgl(struct sock *sk)
 {
-	struct aead_sg_list *sgl = &ctx->tsgl;
+	struct alg_sock *ask = alg_sk(sk);
+	struct aead_ctx *ctx = ask->private;
+	struct aead_tsgl *sgl;
+	struct scatterlist *sg = NULL;
 
-	sg_init_table(sgl->sg, ALG_MAX_PAGES);
-	sgl->cur = 0;
-	ctx->used = 0;
-	ctx->more = 0;
-	ctx->merge = 0;
+	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;
 }
 
-static void aead_put_sgl(struct sock *sk)
+static void aead_pull_tsgl(struct sock *sk, size_t used)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct aead_ctx *ctx = ask->private;
-	struct aead_sg_list *sgl = &ctx->tsgl;
-	struct scatterlist *sg = sgl->sg;
+	struct aead_tsgl *sgl;
+	struct scatterlist *sg;
 	unsigned int i;
 
-	for (i = 0; i < sgl->cur; i++) {
-		if (!sg_page(sg + i))
-			continue;
+	while (!list_empty(&ctx->tsgl_list)) {
+		sgl = list_first_entry(&ctx->tsgl_list, struct aead_tsgl,
+				       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;
+
+			/* in case of error, pull data that is not processed */
+			if (ctx->processed < plen)
+				ctx->processed = 0;
+			else
+				ctx->processed -= plen;
 
-		put_page(sg_page(sg + i));
-		sg_assign_page(sg + i, NULL);
+			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 aead_free_rsgl(struct aead_async_req *areq)
+{
+	struct sock *sk = areq->sk;
+	struct aead_rsgl *rsgl, *tmp;
+
+	list_for_each_entry_safe(rsgl, tmp, &areq->rsgl_list, list) {
+		af_alg_free_sg(&rsgl->sgl);
+		list_del(&rsgl->list);
+		if (rsgl != &areq->first_rsgl)
+			sock_kfree_s(sk, rsgl, sizeof(*rsgl));
 	}
-	aead_reset_ctx(ctx);
+}
+
+static int aead_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, aead_writable(sk), &wait)) {
+			err = 0;
+			break;
+		}
+	}
+	remove_wait_queue(sk_sleep(sk), &wait);
+
+	return err;
 }
 
 static void aead_wmem_wakeup(struct sock *sk)
@@ -146,6 +267,7 @@ static int aead_wait_for_data(struct sock *sk, unsigned flags)
 		return -EAGAIN;
 
 	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+
 	add_wait_queue(sk_sleep(sk), &wait);
 	for (;;) {
 		if (signal_pending(current))
@@ -169,8 +291,6 @@ static void aead_data_wakeup(struct sock *sk)
 	struct aead_ctx *ctx = ask->private;
 	struct socket_wq *wq;
 
-	if (ctx->more)
-		return;
 	if (!ctx->used)
 		return;
 
@@ -189,14 +309,13 @@ 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 aead_ctx *ctx = ask->private;
-	unsigned ivsize =
-		crypto_aead_ivsize(crypto_aead_reqtfm(&ctx->aead_req));
-	struct aead_sg_list *sgl = &ctx->tsgl;
+	unsigned int ivsize = crypto_aead_ivsize(ctx->aead_tfm);
+	struct aead_tsgl *sgl;
 	struct af_alg_control con = {};
 	long copied = 0;
 	bool enc = 0;
 	bool init = 0;
-	int err = -EINVAL;
+	int err = 0;
 
 	if (msg->msg_controllen) {
 		err = af_alg_cmsg_send(msg, &con);
@@ -220,8 +339,10 @@ static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	}
 
 	lock_sock(sk);
-	if (!ctx->more && ctx->used)
+	if (!ctx->more && ctx->used) {
+		err = -EINVAL;
 		goto unlock;
+	}
 
 	if (init) {
 		ctx->enc = enc;
@@ -232,11 +353,14 @@ static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	}
 
 	while (size) {
+		struct scatterlist *sg;
 		size_t len = size;
-		struct scatterlist *sg = NULL;
+		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);
@@ -257,57 +381,60 @@ 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);
-			err = -EMSGSIZE;
-			goto unlock;
+			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));
-		while (len) {
-			size_t plen = 0;
 
-			if (sgl->cur >= ALG_MAX_PAGES) {
-				aead_put_sgl(sk);
-				err = -E2BIG;
-				goto unlock;
-			}
+		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;
 
-			sg = sgl->sg + sgl->cur;
 			plen = min_t(size_t, len, PAGE_SIZE);
 
-			sg_assign_page(sg, alloc_page(GFP_KERNEL));
-			err = -ENOMEM;
-			if (!sg_page(sg))
+			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)),
+			err = memcpy_from_msg(page_address(sg_page(sg + i)),
 					      msg, plen);
 			if (err) {
-				__free_page(sg_page(sg));
-				sg_assign_page(sg, NULL);
+				__free_page(sg_page(sg + i));
+				sg_assign_page(sg + i, NULL);
 				goto unlock;
 			}
 
-			sg->offset = 0;
-			sg->length = plen;
+			sg[i].length = plen;
 			len -= plen;
 			ctx->used += plen;
 			copied += plen;
-			sgl->cur++;
 			size -= plen;
-			ctx->merge = plen & (PAGE_SIZE - 1);
-		}
+			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;
-	if (!ctx->more && !aead_sufficient_data(ctx)) {
-		aead_put_sgl(sk);
-		err = -EMSGSIZE;
-	}
 
 unlock:
 	aead_data_wakeup(sk);
@@ -322,15 +449,12 @@ static ssize_t aead_sendpage(struct socket *sock, struct page *page,
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct aead_ctx *ctx = ask->private;
-	struct aead_sg_list *sgl = &ctx->tsgl;
+	struct aead_tsgl *sgl;
 	int err = -EINVAL;
 
 	if (flags & MSG_SENDPAGE_NOTLAST)
 		flags |= MSG_MORE;
 
-	if (sgl->cur >= ALG_MAX_PAGES)
-		return -E2BIG;
-
 	lock_sock(sk);
 	if (!ctx->more && ctx->used)
 		goto unlock;
@@ -339,13 +463,22 @@ static ssize_t aead_sendpage(struct socket *sock, struct page *page,
 		goto done;
 
 	if (!aead_writable(sk)) {
-		/* user space sent too much data */
-		aead_put_sgl(sk);
-		err = -EMSGSIZE;
-		goto unlock;
+		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);
@@ -356,11 +489,6 @@ static ssize_t aead_sendpage(struct socket *sock, struct page *page,
 
 done:
 	ctx->more = flags & MSG_MORE;
-	if (!ctx->more && !aead_sufficient_data(ctx)) {
-		aead_put_sgl(sk);
-		err = -EMSGSIZE;
-	}
-
 unlock:
 	aead_data_wakeup(sk);
 	release_sock(sk);
@@ -368,206 +496,62 @@ static ssize_t aead_sendpage(struct socket *sock, struct page *page,
 	return err ?: size;
 }
 
-#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 aead_async_req *areq = _req->data;
+	struct sock *sk = areq->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_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 = 0;
-	size_t usedpages = 0;
+	unsigned int resultlen;
 
 	lock_sock(sk);
-	if (ctx->more) {
-		err = aead_wait_for_data(sk, flags);
-		if (err)
-			goto unlock;
-	}
 
-	if (!aead_sufficient_data(ctx))
-		goto unlock;
+	BUG_ON(!ctx->inflight);
 
-	used = ctx->used;
-	if (ctx->enc)
-		outlen = used + as;
-	else
-		outlen = used - as;
-
-	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;
-
-	/* take over all tx sgls from ctx */
-	areq->tsgl = sock_kmalloc(sk,
-				  sizeof(*areq->tsgl) * max_t(u32, sgl->cur, 1),
-				  GFP_KERNEL);
-	if (unlikely(!areq->tsgl))
-		goto free;
-
-	sg_init_table(areq->tsgl, max_t(u32, sgl->cur, 1));
-	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 (outlen > usedpages && 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;
+	/* Buffer size written by crypto operation. */
+	resultlen = areq->outlen;
 
-		/* chain the new scatterlist with previous one */
-		if (last_rsgl)
-			af_alg_link_sg(&last_rsgl->sgl, &rsgl->sgl);
-
-		last_rsgl = rsgl;
-
-		iov_iter_advance(&msg->msg_iter, err);
-	}
+	aead_free_rsgl(areq);
+	aead_pull_tsgl(sk, areq->aead_req.cryptlen);
+	sock_kfree_s(sk, areq, areq->areqlen);
+	__sock_put(sk);
+	ctx->inflight--;
 
-	/* ensure output buffer is sufficiently large */
-	if (usedpages < outlen) {
-		err = -EINVAL;
-		goto unlock;
-	}
+	iocb->ki_complete(iocb, err ? err : resultlen, 0);
 
-	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);
-		}
-		goto free;
-	}
-	aead_put_sgl(sk);
-
-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;
+
+	wake_up_interruptible(&aead_aio_finish_wait);
 }
 
-static int aead_recvmsg_sync(struct socket *sock, struct msghdr *msg, int flags)
+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 aead_ctx *ctx = ask->private;
-	unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
-	struct aead_sg_list *sgl = &ctx->tsgl;
-	struct aead_async_rsgl *last_rsgl = NULL;
-	struct aead_async_rsgl *rsgl, *tmp;
+	struct crypto_aead *tfm = ctx->aead_tfm;
+	unsigned int as = crypto_aead_authsize(tfm);
+	unsigned int areqlen =
+		sizeof(struct aead_async_req) + crypto_aead_reqsize(tfm);
+	struct aead_tsgl *tsgl;
+	struct aead_async_req *areq;
+	struct aead_rsgl *last_rsgl = NULL;
+	struct scatterlist tsgl_head[2], *tsgl_head_p;
 	int err = -EINVAL;
-	unsigned long used = 0;
-	size_t outlen = 0;
-	size_t usedpages = 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;
 
 	lock_sock(sk);
 
 	/*
-	 * Please see documentation of aead_request_set_crypt for the
-	 * description of the AEAD memory structure expected from the caller.
+	 * Data length provided by caller via sendmsg/sendpage that has not
+	 * yet been processed.
 	 */
-
-	if (ctx->more) {
-		err = aead_wait_for_data(sk, flags);
-		if (err)
-			goto unlock;
-	}
-
-	/* data length provided by caller via sendmsg/sendpage */
-	used = ctx->used;
+	used = ctx->used - ctx->processed;
 
 	/*
 	 * Make sure sufficient data is present -- note, the same check is
@@ -600,96 +584,151 @@ static int aead_recvmsg_sync(struct socket *sock, struct msghdr *msg, int flags)
 	 */
 	used -= ctx->aead_assoclen;
 
-	/* convert iovecs of output buffers into scatterlists */
+	/* Allocate cipher request for current operation. */
+	areq = sock_kmalloc(sk, areqlen, GFP_KERNEL);
+	if (unlikely(!areq)) {
+		err = -ENOMEM;
+		goto unlock;
+	}
+	areq->areqlen = areqlen;
+	areq->sk = sk;
+	INIT_LIST_HEAD(&areq->rsgl_list);
+
+	/* convert iovecs of output buffers into RX SGL */
 	while (outlen > usedpages && iov_iter_count(&msg->msg_iter)) {
-		size_t seglen = min_t(size_t, iov_iter_count(&msg->msg_iter),
-				      (outlen - usedpages));
+		struct aead_rsgl *rsgl;
+		size_t seglen;
+
+		if (!ctx->used) {
+			err = aead_wait_for_data(sk, flags);
+			if (err)
+				goto free;
+		}
+
+		seglen = min_t(size_t, (outlen - usedpages),
+			       iov_iter_count(&msg->msg_iter));
 
-		if (list_empty(&ctx->list)) {
-			rsgl = &ctx->first_rsgl;
+		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 unlock;
+				goto free;
 			}
 		}
+
 		rsgl->sgl.npages = 0;
-		list_add_tail(&rsgl->list, &ctx->list);
+		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 unlock;
-		usedpages += err;
+			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;
 		iov_iter_advance(&msg->msg_iter, err);
 	}
 
-	/* ensure output buffer is sufficiently large */
+	/*
+	 * 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) {
-		err = -EINVAL;
-		goto unlock;
-	}
+		size_t less = outlen - usedpages;
 
-	sg_mark_end(sgl->sg + sgl->cur - 1);
-	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);
+		if (used < less) {
+			err = -EINVAL;
+			goto free;
+		}
+		used -= less;
+		outlen -= less;
+	}
 
-	err = af_alg_wait_for_completion(ctx->enc ?
-					 crypto_aead_encrypt(&ctx->aead_req) :
-					 crypto_aead_decrypt(&ctx->aead_req),
+	tsgl = list_first_entry(&ctx->tsgl_list, struct aead_tsgl, list);
+	/* Get the head of the SGL we want to process */
+	tsgl_head_p = scatterwalk_ffwd(tsgl_head, tsgl->sg, ctx->processed);
+	BUG_ON(!tsgl_head_p);
+
+	/* Initialize the crypto operation */
+	aead_request_set_crypt(&areq->aead_req, tsgl_head_p,
+			       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);
+	}
 
 	if (err) {
-		/* EBADMSG implies a valid cipher operation took place */
-		if (err == -EBADMSG)
-			aead_put_sgl(sk);
+		/* AIO operation in progress */
+		if (err == -EINPROGRESS) {
+			sock_hold(sk);
+			err = -EIOCBQUEUED;
 
-		goto unlock;
+			/* Remember the TX bytes that were processed. */
+			ctx->processed += ctx->enc ? (outlen - as) :
+						     (outlen + as);
+			ctx->inflight++;
+
+			/* Remember output size that will be generated. */
+			areq->outlen = outlen;
+
+			goto unlock;
+		}
+		/* EBADMSG implies a valid cipher operation took place */
+		else if (err != -EBADMSG)
+			goto free;
 	}
 
-	aead_put_sgl(sk);
-	err = 0;
+	processed = ctx->enc ? (outlen - as) : (outlen + as);
+	/* Remember the TX bytes that were processed. */
+	ctx->processed += processed;
+
+free:
+	aead_free_rsgl(areq);
+	if (areq)
+		sock_kfree_s(sk, areq, areqlen);
+	aead_pull_tsgl(sk, processed);
 
 unlock:
-	list_for_each_entry_safe(rsgl, tmp, &ctx->list, list) {
-		af_alg_free_sg(&rsgl->sgl);
-		list_del(&rsgl->list);
-		if (rsgl != &ctx->first_rsgl)
-			sock_kfree_s(sk, rsgl, sizeof(*rsgl));
-	}
-	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)
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 	struct aead_ctx *ctx = ask->private;
-	unsigned int mask;
+	unsigned int mask = 0;
 
 	sock_poll_wait(file, sk_sleep(sk), wait);
-	mask = 0;
 
 	if (!ctx->more)
 		mask |= POLLIN | POLLRDNORM;
@@ -746,11 +785,14 @@ static void aead_sock_destruct(struct sock *sk)
 {
 	struct alg_sock *ask = alg_sk(sk);
 	struct aead_ctx *ctx = ask->private;
-	unsigned int ivlen = crypto_aead_ivsize(
-				crypto_aead_reqtfm(&ctx->aead_req));
+	unsigned int ivlen = crypto_aead_ivsize(ctx->aead_tfm);
 
 	WARN_ON(atomic_read(&sk->sk_refcnt) != 0);
-	aead_put_sgl(sk);
+
+	/* Suspend caller if AIO operations are in flight. */
+	wait_event_interruptible(aead_aio_finish_wait, (ctx->inflight == 0));
+
+	aead_pull_tsgl(sk, ctx->used);
 	sock_kzfree_s(sk, ctx->iv, ivlen);
 	sock_kfree_s(sk, ctx, ctx->len);
 	af_alg_release_parent(sk);
@@ -760,7 +802,7 @@ static int aead_accept_parent(void *private, struct sock *sk)
 {
 	struct aead_ctx *ctx;
 	struct alg_sock *ask = alg_sk(sk);
-	unsigned int len = sizeof(*ctx) + crypto_aead_reqsize(private);
+	unsigned int len = sizeof(*ctx);
 	unsigned int ivlen = crypto_aead_ivsize(private);
 
 	ctx = sock_kmalloc(sk, len, GFP_KERNEL);
@@ -775,23 +817,20 @@ static int aead_accept_parent(void *private, struct sock *sk)
 	}
 	memset(ctx->iv, 0, ivlen);
 
+	INIT_LIST_HEAD(&ctx->tsgl_list);
 	ctx->len = len;
 	ctx->used = 0;
+	ctx->processed = 0;
 	ctx->more = 0;
 	ctx->merge = 0;
 	ctx->enc = 0;
-	ctx->tsgl.cur = 0;
+	ctx->inflight = 0;
 	ctx->aead_assoclen = 0;
 	af_alg_init_completion(&ctx->completion);
-	sg_init_table(ctx->tsgl.sg, ALG_MAX_PAGES);
-	INIT_LIST_HEAD(&ctx->list);
 
+	ctx->aead_tfm = private;
 	ask->private = ctx;
 
-	aead_request_set_tfm(&ctx->aead_req, private);
-	aead_request_set_callback(&ctx->aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG,
-				  af_alg_complete, &ctx->completion);
-
 	sk->sk_destruct = aead_sock_destruct;
 
 	return 0;
-- 
2.9.3

Re: [PATCH v3 0/2] crypto: AF_ALG memory management fix

[Stephan Müller]

Am Montag, 13. Februar 2017, 11:04:50 CET schrieb Stephan Müller:

Hi Herbert,

as I just saw that you marked my patch with changes requested in patchwork, 
may I ask which changes should be applied?

Ciao
Stephan

Re: [PATCH v3 0/2] crypto: AF_ALG memory management fix

[Herbert Xu]

On Wed, Feb 15, 2017 at 09:47:19AM +0100, Stephan Müller wrote:
> 
> as I just saw that you marked my patch with changes requested in patchwork, 
> may I ask which changes should be applied?

I thought we agreed that we would not do the TX offset thing and
keep the existing semantics of consuming all TX data given an RX
request.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH v3 0/2] crypto: AF_ALG memory management fix

[Stephan Müller]

Am Donnerstag, 16. Februar 2017, 20:10:21 CET schrieb Herbert Xu:

Hi Herbert,

> On Wed, Feb 15, 2017 at 09:47:19AM +0100, Stephan Müller wrote:
> > as I just saw that you marked my patch with changes requested in
> > patchwork,
> > may I ask which changes should be applied?
> 
> I thought we agreed that we would not do the TX offset thing and
> keep the existing semantics of consuming all TX data given an RX
> request.

Ok, will do.

Ciao
Stephan