rxrpc: Remove VLA usage of skcipher

In the quest to remove all stack VLA usage from the kernel[1], this
replaces struct crypto_skcipher and SKCIPHER_REQUEST_ON_STACK() usage
with struct crypto_sync_skcipher and SYNC_SKCIPHER_REQUEST_ON_STACK(),
which uses a fixed stack size.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Cc: David Howells <dhowells@redhat.com>
Cc: linux-afs@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

net/rxrpc/ar-internal.h

@@ -442,7 +442,7 @@ struct rxrpc_connection {
 	struct sk_buff_head	rx_queue;	/* received conn-level packets */
 	const struct rxrpc_security *security;	/* applied security module */
 	struct key		*server_key;	/* security for this service */
-	struct crypto_skcipher	*cipher;	/* encryption handle */
+	struct crypto_sync_skcipher *cipher;	/* encryption handle */
 	struct rxrpc_crypt	csum_iv;	/* packet checksum base */
 	unsigned long		flags;
 	unsigned long		events;

net/rxrpc/rxkad.c

@@ -46,7 +46,7 @@ struct rxkad_level2_hdr {
  * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE
  * packets
  */
-static struct crypto_skcipher *rxkad_ci;
+static struct crypto_sync_skcipher *rxkad_ci;
 static DEFINE_MUTEX(rxkad_ci_mutex);
 
 /*
@@ -54,7 +54,7 @@ static DEFINE_MUTEX(rxkad_ci_mutex);
  */
 static int rxkad_init_connection_security(struct rxrpc_connection *conn)
 {
-	struct crypto_skcipher *ci;
+	struct crypto_sync_skcipher *ci;
 	struct rxrpc_key_token *token;
 	int ret;
 
@@ -63,14 +63,14 @@ static int rxkad_init_connection_security(struct rxrpc_connection *conn)
 	token = conn->params.key->payload.data[0];
 	conn->security_ix = token->security_index;
 
-	ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
+	ci = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
 	if (IS_ERR(ci)) {
 		_debug("no cipher");
 		ret = PTR_ERR(ci);
 		goto error;
 	}
 
-	if (crypto_skcipher_setkey(ci, token->kad->session_key,
+	if (crypto_sync_skcipher_setkey(ci, token->kad->session_key,
 				   sizeof(token->kad->session_key)) < 0)
 		BUG();
 
@@ -104,7 +104,7 @@ error:
 static int rxkad_prime_packet_security(struct rxrpc_connection *conn)
 {
 	struct rxrpc_key_token *token;
-	SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
+	SYNC_SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
 	struct scatterlist sg;
 	struct rxrpc_crypt iv;
 	__be32 *tmpbuf;
@@ -128,7 +128,7 @@ static int rxkad_prime_packet_security(struct rxrpc_connection *conn)
 	tmpbuf[3] = htonl(conn->security_ix);
 
 	sg_init_one(&sg, tmpbuf, tmpsize);
-	skcipher_request_set_tfm(req, conn->cipher);
+	skcipher_request_set_sync_tfm(req, conn->cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x);
 	crypto_skcipher_encrypt(req);
@@ -167,7 +167,7 @@ static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
 	memset(&iv, 0, sizeof(iv));
 
 	sg_init_one(&sg, sechdr, 8);
-	skcipher_request_set_tfm(req, call->conn->cipher);
+	skcipher_request_set_sync_tfm(req, call->conn->cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
 	crypto_skcipher_encrypt(req);
@@ -212,7 +212,7 @@ static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
 	memcpy(&iv, token->kad->session_key, sizeof(iv));
 
 	sg_init_one(&sg[0], sechdr, sizeof(rxkhdr));
-	skcipher_request_set_tfm(req, call->conn->cipher);
+	skcipher_request_set_sync_tfm(req, call->conn->cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg[0], &sg[0], sizeof(rxkhdr), iv.x);
 	crypto_skcipher_encrypt(req);
@@ -250,7 +250,7 @@ static int rxkad_secure_packet(struct rxrpc_call *call,
 			       void *sechdr)
 {
 	struct rxrpc_skb_priv *sp;
-	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
+	SYNC_SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 	struct rxrpc_crypt iv;
 	struct scatterlist sg;
 	u32 x, y;
@@ -279,7 +279,7 @@ static int rxkad_secure_packet(struct rxrpc_call *call,
 	call->crypto_buf[1] = htonl(x);
 
 	sg_init_one(&sg, call->crypto_buf, 8);
-	skcipher_request_set_tfm(req, call->conn->cipher);
+	skcipher_request_set_sync_tfm(req, call->conn->cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
 	crypto_skcipher_encrypt(req);
@@ -352,7 +352,7 @@ static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
 	/* start the decryption afresh */
 	memset(&iv, 0, sizeof(iv));
 
-	skcipher_request_set_tfm(req, call->conn->cipher);
+	skcipher_request_set_sync_tfm(req, call->conn->cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, sg, sg, 8, iv.x);
 	crypto_skcipher_decrypt(req);
@@ -450,7 +450,7 @@ static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
 	token = call->conn->params.key->payload.data[0];
 	memcpy(&iv, token->kad->session_key, sizeof(iv));
 
-	skcipher_request_set_tfm(req, call->conn->cipher);
+	skcipher_request_set_sync_tfm(req, call->conn->cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, sg, sg, len, iv.x);
 	crypto_skcipher_decrypt(req);
@@ -506,7 +506,7 @@ static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 			       unsigned int offset, unsigned int len,
 			       rxrpc_seq_t seq, u16 expected_cksum)
 {
-	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
+	SYNC_SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
 	struct rxrpc_crypt iv;
 	struct scatterlist sg;
 	bool aborted;
@@ -529,7 +529,7 @@ static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 	call->crypto_buf[1] = htonl(x);
 
 	sg_init_one(&sg, call->crypto_buf, 8);
-	skcipher_request_set_tfm(req, call->conn->cipher);
+	skcipher_request_set_sync_tfm(req, call->conn->cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
 	crypto_skcipher_encrypt(req);
@@ -755,7 +755,7 @@ static void rxkad_encrypt_response(struct rxrpc_connection *conn,
 				   struct rxkad_response *resp,
 				   const struct rxkad_key *s2)
 {
-	SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
+	SYNC_SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
 	struct rxrpc_crypt iv;
 	struct scatterlist sg[1];
 
@@ -764,7 +764,7 @@ static void rxkad_encrypt_response(struct rxrpc_connection *conn,
 
 	sg_init_table(sg, 1);
 	sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
-	skcipher_request_set_tfm(req, conn->cipher);
+	skcipher_request_set_sync_tfm(req, conn->cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
 	crypto_skcipher_encrypt(req);
@@ -1021,7 +1021,7 @@ static void rxkad_decrypt_response(struct rxrpc_connection *conn,
 				   struct rxkad_response *resp,
 				   const struct rxrpc_crypt *session_key)
 {
-	SKCIPHER_REQUEST_ON_STACK(req, rxkad_ci);
+	SYNC_SKCIPHER_REQUEST_ON_STACK(req, rxkad_ci);
 	struct scatterlist sg[1];
 	struct rxrpc_crypt iv;
 
@@ -1031,7 +1031,7 @@ static void rxkad_decrypt_response(struct rxrpc_connection *conn,
 	ASSERT(rxkad_ci != NULL);
 
 	mutex_lock(&rxkad_ci_mutex);
-	if (crypto_skcipher_setkey(rxkad_ci, session_key->x,
+	if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x,
 				   sizeof(*session_key)) < 0)
 		BUG();
 
@@ -1039,7 +1039,7 @@ static void rxkad_decrypt_response(struct rxrpc_connection *conn,
 
 	sg_init_table(sg, 1);
 	sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
-	skcipher_request_set_tfm(req, rxkad_ci);
+	skcipher_request_set_sync_tfm(req, rxkad_ci);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
 	crypto_skcipher_decrypt(req);
@@ -1218,7 +1218,7 @@ static void rxkad_clear(struct rxrpc_connection *conn)
 	_enter("");
 
 	if (conn->cipher)
-		crypto_free_skcipher(conn->cipher);
+		crypto_free_sync_skcipher(conn->cipher);
 }
 
 /*
@@ -1228,7 +1228,7 @@ static int rxkad_init(void)
 {
 	/* pin the cipher we need so that the crypto layer doesn't invoke
 	 * keventd to go get it */
-	rxkad_ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
+	rxkad_ci = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
 	return PTR_ERR_OR_ZERO(rxkad_ci);
 }
 
@@ -1238,7 +1238,7 @@ static int rxkad_init(void)
 static void rxkad_exit(void)
 {
 	if (rxkad_ci)
-		crypto_free_skcipher(rxkad_ci);
+		crypto_free_sync_skcipher(rxkad_ci);
 }
 
 /*