crypto: algif_aead - Only wake up when ctx->more is zero

AEAD does not support partial requests so we must not wake up
while ctx->more is set.  In order to distinguish between the
case of no data sent yet and a zero-length request, a new init
flag has been added to ctx.

SKCIPHER has also been modified to ensure that at least a block
of data is available if there is more data to come.

Fixes: 2d97591e ("crypto: af_alg - consolidation of...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/af_alg.c

@@ -635,6 +635,7 @@ void af_alg_pull_tsgl(struct sock *sk, size_t used, struct scatterlist *dst,
 
 	if (!ctx->used)
 		ctx->merge = 0;
+	ctx->init = ctx->more;
 }
 EXPORT_SYMBOL_GPL(af_alg_pull_tsgl);
 
@@ -734,9 +735,10 @@ EXPORT_SYMBOL_GPL(af_alg_wmem_wakeup);
  *
  * @sk socket of connection to user space
  * @flags If MSG_DONTWAIT is set, then only report if function would sleep
+ * @min Set to minimum request size if partial requests are allowed.
  * @return 0 when writable memory is available, < 0 upon error
  */
-int af_alg_wait_for_data(struct sock *sk, unsigned flags)
+int af_alg_wait_for_data(struct sock *sk, unsigned flags, unsigned min)
 {
 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
 	struct alg_sock *ask = alg_sk(sk);
@@ -754,7 +756,9 @@ int af_alg_wait_for_data(struct sock *sk, unsigned flags)
 		if (signal_pending(current))
 			break;
 		timeout = MAX_SCHEDULE_TIMEOUT;
-		if (sk_wait_event(sk, &timeout, (ctx->used || !ctx->more),
+		if (sk_wait_event(sk, &timeout,
+				  ctx->init && (!ctx->more ||
+						(min && ctx->used >= min)),
 				  &wait)) {
 			err = 0;
 			break;
@@ -843,7 +847,7 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
 	}
 
 	lock_sock(sk);
-	if (!ctx->more && ctx->used) {
+	if (ctx->init && (init || !ctx->more)) {
 		err = -EINVAL;
 		goto unlock;
 	}
@@ -854,6 +858,7 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
 			memcpy(ctx->iv, con.iv->iv, ivsize);
 
 		ctx->aead_assoclen = con.aead_assoclen;
+		ctx->init = true;
 	}
 
 	while (size) {

crypto/algif_aead.c

@@ -106,8 +106,8 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
 	size_t usedpages = 0;		/* [in]  RX bufs to be used from user */
 	size_t processed = 0;		/* [in]  TX bufs to be consumed */
 
-	if (!ctx->used) {
-		err = af_alg_wait_for_data(sk, flags);
+	if (!ctx->init || ctx->more) {
+		err = af_alg_wait_for_data(sk, flags, 0);
 		if (err)
 			return err;
 	}

crypto/algif_skcipher.c

@@ -61,8 +61,8 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 	int err = 0;
 	size_t len = 0;
 
-	if (!ctx->used) {
-		err = af_alg_wait_for_data(sk, flags);
+	if (!ctx->init || (ctx->more && ctx->used < bs)) {
+		err = af_alg_wait_for_data(sk, flags, bs);
 		if (err)
 			return err;
 	}

include/crypto/if_alg.h

@@ -135,6 +135,7 @@ struct af_alg_async_req {
  *			SG?
  * @enc:		Cryptographic operation to be performed when
  *			recvmsg is invoked.
+ * @init:		True if metadata has been sent.
  * @len:		Length of memory allocated for this data structure.
  */
 struct af_alg_ctx {
@@ -151,6 +152,7 @@ struct af_alg_ctx {
 	bool more;
 	bool merge;
 	bool enc;
+	bool init;
 
 	unsigned int len;
 };
@@ -226,7 +228,7 @@ unsigned int af_alg_count_tsgl(struct sock *sk, size_t bytes, size_t offset);
 void af_alg_pull_tsgl(struct sock *sk, size_t used, struct scatterlist *dst,
 		      size_t dst_offset);
 void af_alg_wmem_wakeup(struct sock *sk);
-int af_alg_wait_for_data(struct sock *sk, unsigned flags);
+int af_alg_wait_for_data(struct sock *sk, unsigned flags, unsigned min);
 int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
 		   unsigned int ivsize);
 ssize_t af_alg_sendpage(struct socket *sock, struct page *page,