rxrpc: Clone received jumbo subpackets and queue separately

Split up received jumbo packets into separate skbuffs by cloning the
original skbuff for each subpacket and setting the offset and length of the
data in that subpacket in the skbuff's private data.  The subpackets are
then placed on the recvmsg queue separately.  The security class then gets
to revise the offset and length to remove its metadata.

If we fail to clone a packet, we just drop it and let the peer resend it.
The original packet gets used for the final subpacket.

This should make it easier to handle parallel decryption of the subpackets.
It also simplifies the handling of lost or misordered packets in the
queuing/buffering loop as the possibility of overlapping jumbo packets no
longer needs to be considered.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

1 files changed, 14 insertions, 90 deletions

diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c
index 77cde6311559..401aae687830 100644
--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -222,7 +222,6 @@ static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
 	rxrpc_serial_t serial;
 	rxrpc_seq_t hard_ack, top;
 	bool last = false;
-	u8 subpacket;
 	int ix;
 
 	_enter("%d", call->debug_id);
@@ -237,11 +236,9 @@ static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
 	rxrpc_see_skb(skb, rxrpc_skb_rotated);
 	sp = rxrpc_skb(skb);
 
-	subpacket = call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
-	serial = sp->hdr.serial + subpacket;
+	serial = sp->hdr.serial;
 
-	if (subpacket == sp->nr_subpackets - 1 &&
-	    sp->rx_flags & RXRPC_SKB_INCL_LAST)
+	if (sp->hdr.flags & RXRPC_LAST_PACKET)
 		last = true;
 
 	call->rxtx_buffer[ix] = NULL;
@@ -266,80 +263,15 @@ static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
 }
 
 /*
- * Decrypt and verify a (sub)packet.  The packet's length may be changed due to
- * padding, but if this is the case, the packet length will be resident in the
- * socket buffer.  Note that we can't modify the master skb info as the skb may
- * be the home to multiple subpackets.
+ * Decrypt and verify a DATA packet.
  */
-static int rxrpc_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
-			       u8 annotation,
-			       unsigned int offset, unsigned int len)
+static int rxrpc_verify_data(struct rxrpc_call *call, struct sk_buff *skb)
 {
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
-	rxrpc_seq_t seq = sp->hdr.seq;
-	u16 cksum = sp->hdr.cksum;
-	u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;
 
-	_enter("");
-
-	/* For all but the head jumbo subpacket, the security checksum is in a
-	 * jumbo header immediately prior to the data.
-	 */
-	if (subpacket > 0) {
-		__be16 tmp;
-		if (skb_copy_bits(skb, offset - 2, &tmp, 2) < 0)
-			BUG();
-		cksum = ntohs(tmp);
-		seq += subpacket;
-	}
-
-	return call->security->verify_packet(call, skb, offset, len,
-					     seq, cksum);
-}
-
-/*
- * Locate the data within a packet.  This is complicated by:
- *
- * (1) An skb may contain a jumbo packet - so we have to find the appropriate
- *     subpacket.
- *
- * (2) The (sub)packets may be encrypted and, if so, the encrypted portion
- *     contains an extra header which includes the true length of the data,
- *     excluding any encrypted padding.
- */
-static int rxrpc_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
-			     u8 *_annotation,
-			     unsigned int *_offset, unsigned int *_len,
-			     bool *_last)
-{
-	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
-	unsigned int offset = sizeof(struct rxrpc_wire_header);
-	unsigned int len;
-	bool last = false;
-	int ret;
-	u8 annotation = *_annotation;
-	u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;
-
-	/* Locate the subpacket */
-	offset += subpacket * RXRPC_JUMBO_SUBPKTLEN;
-	len = skb->len - offset;
-	if (subpacket < sp->nr_subpackets - 1)
-		len = RXRPC_JUMBO_DATALEN;
-	else if (sp->rx_flags & RXRPC_SKB_INCL_LAST)
-		last = true;
-
-	if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
-		ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
-		if (ret < 0)
-			return ret;
-		*_annotation |= RXRPC_RX_ANNO_VERIFIED;
-	}
-
-	*_offset = offset;
-	*_len = len;
-	*_last = last;
-	call->security->locate_data(call, skb, _offset, _len);
-	return 0;
+	if (sp->flags & RXRPC_RX_VERIFIED)
+		return 0;
+	return call->security->verify_packet(call, skb);
 }
 
 /*
@@ -356,13 +288,11 @@ static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 	rxrpc_serial_t serial;
 	rxrpc_seq_t hard_ack, top, seq;
 	size_t remain;
-	bool rx_pkt_last;
 	unsigned int rx_pkt_offset, rx_pkt_len;
 	int ix, copy, ret = -EAGAIN, ret2;
 
 	rx_pkt_offset = call->rx_pkt_offset;
 	rx_pkt_len = call->rx_pkt_len;
-	rx_pkt_last = call->rx_pkt_last;
 
 	if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
 		seq = call->rx_hard_ack;
@@ -391,7 +321,6 @@ static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 
 		if (!(flags & MSG_PEEK)) {
 			serial = sp->hdr.serial;
-			serial += call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
 			trace_rxrpc_receive(call, rxrpc_receive_front,
 					    serial, seq);
 		}
@@ -400,10 +329,9 @@ static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 			sock_recv_timestamp(msg, sock->sk, skb);
 
 		if (rx_pkt_offset == 0) {
-			ret2 = rxrpc_locate_data(call, skb,
-						 &call->rxtx_annotations[ix],
-						 &rx_pkt_offset, &rx_pkt_len,
-						 &rx_pkt_last);
+			ret2 = rxrpc_verify_data(call, skb);
+			rx_pkt_offset = sp->offset;
+			rx_pkt_len = sp->len;
 			trace_rxrpc_recvdata(call, rxrpc_recvmsg_next, seq,
 					     rx_pkt_offset, rx_pkt_len, ret2);
 			if (ret2 < 0) {
@@ -443,16 +371,13 @@ static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 		}
 
 		/* The whole packet has been transferred. */
-		if (!(flags & MSG_PEEK))
-			rxrpc_rotate_rx_window(call);
+		if (sp->hdr.flags & RXRPC_LAST_PACKET)
+			ret = 1;
 		rx_pkt_offset = 0;
 		rx_pkt_len = 0;
 
-		if (rx_pkt_last) {
-			ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
-			ret = 1;
-			goto out;
-		}
+		if (!(flags & MSG_PEEK))
+			rxrpc_rotate_rx_window(call);
 
 		seq++;
 	}
@@ -461,7 +386,6 @@ out:
 	if (!(flags & MSG_PEEK)) {
 		call->rx_pkt_offset = rx_pkt_offset;
 		call->rx_pkt_len = rx_pkt_len;
-		call->rx_pkt_last = rx_pkt_last;
 	}
 done:
 	trace_rxrpc_recvdata(call, rxrpc_recvmsg_data_return, seq,