tls/device: Use splice_eof() to flush

Allow splice to end a TLS record after prematurely ending a splice/sendfile
due to getting an EOF condition (->splice_read() returned 0) after splice
had called TLS with a sendmsg() with MSG_MORE set when the user didn't set
MSG_MORE.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/CAHk-=wh=V579PDYvkpnTobCLGczbgxpMgGmmhqiTyE34Cpi5Gg@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
cc: Chuck Lever <chuck.lever@oracle.com>
cc: Boris Pismenny <borisp@nvidia.com>
cc: John Fastabend <john.fastabend@gmail.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/tls/tls.h

@@ -116,6 +116,7 @@ ssize_t tls_sw_splice_read(struct socket *sock, loff_t *ppos,
 			   size_t len, unsigned int flags);
 
 int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
+void tls_device_splice_eof(struct socket *sock);
 int tls_device_sendpage(struct sock *sk, struct page *page,
 			int offset, size_t size, int flags);
 int tls_tx_records(struct sock *sk, int flags);

net/tls/tls_device.c

@@ -590,6 +590,29 @@ int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	return rc;
 }
 
+void tls_device_splice_eof(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct tls_context *tls_ctx = tls_get_ctx(sk);
+	union tls_iter_offset iter;
+	struct iov_iter iov_iter = {};
+
+	if (!tls_is_partially_sent_record(tls_ctx))
+		return;
+
+	mutex_lock(&tls_ctx->tx_lock);
+	lock_sock(sk);
+
+	if (tls_is_partially_sent_record(tls_ctx)) {
+		iov_iter_bvec(&iov_iter, ITER_SOURCE, NULL, 0, 0);
+		iter.msg_iter = &iov_iter;
+		tls_push_data(sk, iter, 0, 0, TLS_RECORD_TYPE_DATA, NULL);
+	}
+
+	release_sock(sk);
+	mutex_unlock(&tls_ctx->tx_lock);
+}
+
 int tls_device_sendpage(struct sock *sk, struct page *page,
 			int offset, size_t size, int flags)
 {

net/tls/tls_main.c

@@ -1044,10 +1044,12 @@ static void build_protos(struct proto prot[TLS_NUM_CONFIG][TLS_NUM_CONFIG],
 #ifdef CONFIG_TLS_DEVICE
 	prot[TLS_HW][TLS_BASE] = prot[TLS_BASE][TLS_BASE];
 	prot[TLS_HW][TLS_BASE].sendmsg		= tls_device_sendmsg;
+	prot[TLS_HW][TLS_BASE].splice_eof	= tls_device_splice_eof;
 	prot[TLS_HW][TLS_BASE].sendpage		= tls_device_sendpage;
 
 	prot[TLS_HW][TLS_SW] = prot[TLS_BASE][TLS_SW];
 	prot[TLS_HW][TLS_SW].sendmsg		= tls_device_sendmsg;
+	prot[TLS_HW][TLS_SW].splice_eof		= tls_device_splice_eof;
 	prot[TLS_HW][TLS_SW].sendpage		= tls_device_sendpage;
 
 	prot[TLS_BASE][TLS_HW] = prot[TLS_BASE][TLS_SW];