rxrpc: Allocate an skcipher each time needed rather than reusing

In the rxkad security class, allocate the skcipher used to do packet
encryption and decription rather than allocating one up front and reusing
it for each packet.  Reusing the skcipher precludes doing crypto in
parallel.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

net/rxrpc/ar-internal.h

@@ -583,7 +583,6 @@ struct rxrpc_call {
 	unsigned long		expect_term_by;	/* When we expect call termination by */
 	u32			next_rx_timo;	/* Timeout for next Rx packet (jif) */
 	u32			next_req_timo;	/* Timeout for next Rx request packet (jif) */
-	struct skcipher_request	*cipher_req;	/* Packet cipher request buffer */
 	struct timer_list	timer;		/* Combined event timer */
 	struct work_struct	processor;	/* Event processor */
 	rxrpc_notify_rx_t	notify_rx;	/* kernel service Rx notification function */
@@ -597,7 +596,6 @@ struct rxrpc_call {
 	struct rxrpc_txbuf	*tx_pending;	/* Tx buffer being filled */
 	wait_queue_head_t	waitq;		/* Wait queue for channel or Tx */
 	s64			tx_total_len;	/* Total length left to be transmitted (or -1) */
-	__be32			crypto_buf[2];	/* Temporary packet crypto buffer */
 	unsigned long		user_call_ID;	/* user-defined call ID */
 	unsigned long		flags;
 	unsigned long		events;

net/rxrpc/rxkad.c

@@ -233,16 +233,8 @@ static int rxkad_prime_packet_security(struct rxrpc_connection *conn,
 static struct skcipher_request *rxkad_get_call_crypto(struct rxrpc_call *call)
 {
 	struct crypto_skcipher *tfm = &call->conn->rxkad.cipher->base;
-	struct skcipher_request	*cipher_req = call->cipher_req;
 
-	if (!cipher_req) {
-		cipher_req = skcipher_request_alloc(tfm, GFP_NOFS);
-		if (!cipher_req)
-			return NULL;
-		call->cipher_req = cipher_req;
-	}
-
-	return cipher_req;
+	return skcipher_request_alloc(tfm, GFP_NOFS);
 }
 
 /*
@@ -250,9 +242,6 @@ static struct skcipher_request *rxkad_get_call_crypto(struct rxrpc_call *call)
  */
 static void rxkad_free_call_crypto(struct rxrpc_call *call)
 {
-	if (call->cipher_req)
-		skcipher_request_free(call->cipher_req);
-	call->cipher_req = NULL;
 }
 
 /*
@@ -348,6 +337,9 @@ static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
 	struct skcipher_request	*req;
 	struct rxrpc_crypt iv;
 	struct scatterlist sg;
+	union {
+		__be32 buf[2];
+	} crypto __aligned(8);
 	u32 x, y;
 	int ret;
 
@@ -372,17 +364,17 @@ static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
 	/* calculate the security checksum */
 	x = (ntohl(txb->wire.cid) & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
 	x |= txb->seq & 0x3fffffff;
-	call->crypto_buf[0] = txb->wire.callNumber;
-	call->crypto_buf[1] = htonl(x);
+	crypto.buf[0] = txb->wire.callNumber;
+	crypto.buf[1] = htonl(x);
 
-	sg_init_one(&sg, call->crypto_buf, 8);
+	sg_init_one(&sg, crypto.buf, 8);
 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
 	crypto_skcipher_encrypt(req);
 	skcipher_request_zero(req);
 
-	y = ntohl(call->crypto_buf[1]);
+	y = ntohl(crypto.buf[1]);
 	y = (y >> 16) & 0xffff;
 	if (y == 0)
 		y = 1; /* zero checksums are not permitted */
@@ -403,6 +395,7 @@ static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
 		break;
 	}
 
+	skcipher_request_free(req);
 	_leave(" = %d [set %x]", ret, y);
 	return ret;
 }
@@ -593,8 +586,12 @@ static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb)
 	struct skcipher_request	*req;
 	struct rxrpc_crypt iv;
 	struct scatterlist sg;
+	union {
+		__be32 buf[2];
+	} crypto __aligned(8);
 	rxrpc_seq_t seq = sp->hdr.seq;
 	bool aborted;
+	int ret;
 	u16 cksum;
 	u32 x, y;
 
@@ -614,17 +611,17 @@ static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb)
 	/* validate the security checksum */
 	x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
 	x |= seq & 0x3fffffff;
-	call->crypto_buf[0] = htonl(call->call_id);
-	call->crypto_buf[1] = htonl(x);
+	crypto.buf[0] = htonl(call->call_id);
+	crypto.buf[1] = htonl(x);
 
-	sg_init_one(&sg, call->crypto_buf, 8);
+	sg_init_one(&sg, crypto.buf, 8);
 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
 	crypto_skcipher_encrypt(req);
 	skcipher_request_zero(req);
 
-	y = ntohl(call->crypto_buf[1]);
+	y = ntohl(crypto.buf[1]);
 	cksum = (y >> 16) & 0xffff;
 	if (cksum == 0)
 		cksum = 1; /* zero checksums are not permitted */
@@ -637,15 +634,22 @@ static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb)
 
 	switch (call->conn->params.security_level) {
 	case RXRPC_SECURITY_PLAIN:
-		return 0;
+		ret = 0;
+		break;
 	case RXRPC_SECURITY_AUTH:
-		return rxkad_verify_packet_1(call, skb, seq, req);
+		ret = rxkad_verify_packet_1(call, skb, seq, req);
+		break;
 	case RXRPC_SECURITY_ENCRYPT:
-		return rxkad_verify_packet_2(call, skb, seq, req);
+		ret = rxkad_verify_packet_2(call, skb, seq, req);
+		break;
 	default:
-		return -ENOANO;
+		ret = -ENOANO;
+		break;
 	}
 
+	skcipher_request_free(req);
+	return ret;
+
 protocol_error:
 	if (aborted)
 		rxrpc_send_abort_packet(call);