rxrpc: Ask the security class how much space to allow in a packet

Ask the security class how much header and trailer space to allow for when
allocating a packet, given how much data is remaining.

This will allow the rxgk security class to stick both a trailer in as well
as a header as appropriate in the future.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 13 insertions, 28 deletions

diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 367654a558c2..af8ad6c30b9f 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -327,7 +327,7 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
 			rxrpc_send_ack_packet(call, false, NULL);
 
 		if (!skb) {
-			size_t size, chunk, max, space;
+			size_t remain, bufsize, chunk, offset;
 
 			_debug("alloc");
 
@@ -342,24 +342,21 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
 					goto maybe_error;
 			}
 
-			max = RXRPC_JUMBO_DATALEN;
-			max -= call->conn->security_size;
-			max &= ~(call->conn->size_align - 1UL);
-
-			chunk = max;
-			if (chunk > msg_data_left(msg) && !more)
-				chunk = msg_data_left(msg);
-
-			space = chunk + call->conn->size_align;
-			space &= ~(call->conn->size_align - 1UL);
-
-			size = space + call->conn->security_size;
+			/* Work out the maximum size of a packet.  Assume that
+			 * the security header is going to be in the padded
+			 * region (enc blocksize), but the trailer is not.
+			 */
+			remain = more ? INT_MAX : msg_data_left(msg);
+			ret = call->conn->security->how_much_data(call, remain,
+								  &bufsize, &chunk, &offset);
+			if (ret < 0)
+				goto maybe_error;
 
-			_debug("SIZE: %zu/%zu/%zu", chunk, space, size);
+			_debug("SIZE: %zu/%zu @%zu", chunk, bufsize, offset);
 
 			/* create a buffer that we can retain until it's ACK'd */
 			skb = sock_alloc_send_skb(
-				sk, size, msg->msg_flags & MSG_DONTWAIT, &ret);
+				sk, bufsize, msg->msg_flags & MSG_DONTWAIT, &ret);
 			if (!skb)
 				goto maybe_error;
 
@@ -371,8 +368,7 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
 
 			ASSERTCMP(skb->mark, ==, 0);
 
-			_debug("HS: %u", call->conn->security_size);
-			__skb_put(skb, call->conn->security_size);
+			__skb_put(skb, offset);
 
 			sp->remain = chunk;
 			if (sp->remain > skb_tailroom(skb))
@@ -421,17 +417,6 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
 		    (msg_data_left(msg) == 0 && !more)) {
 			struct rxrpc_connection *conn = call->conn;
 			uint32_t seq;
-			size_t pad;
-
-			/* pad out if we're using security */
-			if (conn->security_ix) {
-				pad = conn->security_size + skb->mark;
-				pad = conn->size_align - pad;
-				pad &= conn->size_align - 1;
-				_debug("pad %zu", pad);
-				if (pad)
-					skb_put_zero(skb, pad);
-			}
 
 			seq = call->tx_top + 1;