[PATCH RFC 11/15] SUNRPC: Add infrastructure for async RPC_AUTH_TLS probe

[Chuck Lever <chuck.lever@oracle.com>]

Introduce helpers for sending an RPC_AUTH_TLS probe, waiting for
it, and then parsing the reply. These will be used to handle the
reconnect case.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 include/linux/sunrpc/clnt.h |    1 +
 include/linux/sunrpc/xprt.h |   13 ++++++++++
 net/sunrpc/clnt.c           |   58 +++++++++++++++++++++++++++++++++++++++++++
 net/sunrpc/xprt.c           |    1 +
 net/sunrpc/xprtsock.c       |   56 ++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 129 insertions(+)

diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index e10a19d136ca..15fd84e4c321 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -209,6 +209,7 @@ int		rpc_call_sync(struct rpc_clnt *clnt,
 			      unsigned int flags);
 struct rpc_task *rpc_call_null(struct rpc_clnt *clnt, struct rpc_cred *cred,
 			       int flags);
+void		rpc_starttls_async(struct rpc_task *task);
 int		rpc_restart_call_prepare(struct rpc_task *);
 int		rpc_restart_call(struct rpc_task *);
 void		rpc_setbufsize(struct rpc_clnt *, unsigned int, unsigned int);
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 8d654bc35dce..cbb0fe738d97 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -159,6 +159,7 @@ struct rpc_xprt_ops {
 	void		(*disable_swap)(struct rpc_xprt *xprt);
 	void		(*inject_disconnect)(struct rpc_xprt *xprt);
 	int		(*tls_handshake_sync)(struct rpc_xprt *xprt);
+	int		(*tls_handshake_async)(struct rpc_xprt *xprt);
 	int		(*bc_setup)(struct rpc_xprt *xprt,
 				    unsigned int min_reqs);
 	size_t		(*bc_maxpayload)(struct rpc_xprt *xprt);
@@ -204,6 +205,7 @@ struct rpc_xprt {
 	size_t			max_payload;	/* largest RPC payload size,
 						   in bytes */
 
+	struct rpc_wait_queue	probing;	/* requests waiting on TLS probe */
 	struct rpc_wait_queue	binding;	/* requests waiting on rpcbind */
 	struct rpc_wait_queue	sending;	/* requests waiting to send */
 	struct rpc_wait_queue	pending;	/* requests in flight */
@@ -436,6 +438,7 @@ void			xprt_release_write(struct rpc_xprt *, struct rpc_task *);
 #define XPRT_CWND_WAIT		(10)
 #define XPRT_WRITE_SPACE	(11)
 #define XPRT_SND_IS_COOKIE	(12)
+#define XPRT_PROBING		(13)
 
 static inline void xprt_set_connected(struct rpc_xprt *xprt)
 {
@@ -506,4 +509,14 @@ static inline int xprt_test_and_set_binding(struct rpc_xprt *xprt)
 	return test_and_set_bit(XPRT_BINDING, &xprt->state);
 }
 
+static inline void xprt_clear_probing(struct rpc_xprt *xprt)
+{
+	clear_bit(XPRT_PROBING, &xprt->state);
+}
+
+static inline int xprt_test_and_set_probing(struct rpc_xprt *xprt)
+{
+	return test_and_set_bit(XPRT_PROBING, &xprt->state);
+}
+
 #endif /* _LINUX_SUNRPC_XPRT_H */
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 1601a06deaf5..e9a6622dba68 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -2829,6 +2829,64 @@ static int rpc_starttls_sync(struct rpc_clnt *clnt)
 	return err;
 }
 
+static void rpc_probe_tls_done(struct rpc_task *task, void *data)
+{
+	struct rpc_xprt *xprt = data;
+
+	if (task->tk_status < 0) {
+		trace_rpc_tls_unavailable(task->tk_client, xprt);
+		xprt_clear_probing(xprt);
+		rpc_wake_up_status(&xprt->probing, task->tk_status);
+		return;
+	}
+
+	/* Send ClientHello; a second callback will wake the waiting task */
+	if (xprt->ops->tls_handshake_async(xprt)) {
+		trace_rpc_tls_not_started(task->tk_client, xprt);
+		xprt_clear_probing(xprt);
+		rpc_wake_up_status(&xprt->probing, -EACCES);
+	}
+}
+
+static void rpc_probe_tls_release(void *data)
+{
+	struct rpc_xprt *xprt = data;
+
+	xprt_put(xprt);
+}
+
+static const struct rpc_call_ops rpc_ops_probe_tls = {
+	.rpc_call_done	= rpc_probe_tls_done,
+	.rpc_release	= rpc_probe_tls_release,
+};
+
+/**
+ * rpc_starttls_async - Asynchronously establish a TLS session
+ * @task: an RPC task waiting for a TLS session
+ *
+ */
+void rpc_starttls_async(struct rpc_task *task)
+{
+	struct rpc_xprt *xprt = xprt_get(task->tk_xprt);
+
+	rpc_sleep_on_timeout(&xprt->probing, task, NULL,
+			     jiffies + xprt->connect_timeout);
+	if (xprt_test_and_set_probing(xprt)) {
+		xprt_put(xprt);
+		return;
+	}
+
+	/*
+	 * RPC_TASK_TLSCRED: use an RPC_AUTH_TLS cred instead of AUTH_NULL
+	 * RPC_TASK_SWAPPER: insert the task at the head of the transmit queue
+	 * RPC_TASK_CORK: stop sending after this Call is transmitted
+	 */
+	rpc_put_task(rpc_call_null_helper(task->tk_client, xprt, NULL,
+		     RPC_TASK_TLSCRED | RPC_TASK_SWAPPER | RPC_TASK_CORK,
+		     &rpc_ops_probe_tls, xprt));
+}
+EXPORT_SYMBOL_GPL(rpc_starttls_async);
+
 struct rpc_cb_add_xprt_calldata {
 	struct rpc_xprt_switch *xps;
 	struct rpc_xprt *xprt;
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 4b303b945b51..762281dba077 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -2016,6 +2016,7 @@ static void xprt_init(struct rpc_xprt *xprt, struct net *net)
 	xprt->cwnd = RPC_INITCWND;
 	xprt->bind_index = 0;
 
+	rpc_init_wait_queue(&xprt->probing, "xprt_probing");
 	rpc_init_wait_queue(&xprt->binding, "xprt_binding");
 	rpc_init_wait_queue(&xprt->pending, "xprt_pending");
 	rpc_init_wait_queue(&xprt->sending, "xprt_sending");
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index bbba9747f68d..bb8c32002ce7 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -2378,6 +2378,46 @@ static int xs_tcp_tls_handshake_sync(struct rpc_xprt *xprt)
 	return rc;
 }
 
+/**
+ * xs_tcp_tls_handshake_wake - TLS handshake completion handler
+ * @data: address of xprt to wake
+ * @status: status of handshake
+ *
+ */
+static void xs_tcp_tls_handshake_wake(void *data, int status)
+{
+	struct rpc_xprt *xprt = data;
+	struct sock_xprt *transport =
+				container_of(xprt, struct sock_xprt, xprt);
+
+	xs_tcp_clear_discard(transport);
+	xprt_clear_probing(xprt);
+	rpc_wake_up_status(&xprt->probing, status < 0 ? -EACCES : 0);
+	xprt_put(xprt);
+}
+
+/**
+ * xs_tcp_tls_handshake_async - Start a TLS handshake
+ * @xprt: transport on which to perform handshake
+ *
+ * Caller ensures there will be no other traffic on this transport.
+ *
+ * Return values:
+ *   %0: Handshake initiated; @xprt will be awoken when it's done.
+ *   Negative errno: handshake was not started.
+ */
+static int xs_tcp_tls_handshake_async(struct rpc_xprt *xprt)
+{
+	struct sock_xprt *transport =
+				container_of(xprt, struct sock_xprt, xprt);
+
+	WRITE_ONCE(transport->recv.ignore_dr, true);
+	return tls_client_hello_x509(transport->sock,
+				     xs_tcp_tls_handshake_wake, xprt_get(xprt),
+				     TLSH_DEFAULT_PRIORITIES, TLSH_NO_PEERID,
+				     TLSH_NO_CERT);
+}
+
 #else /* CONFIG_TLS */
 
 /**
@@ -2394,6 +2434,21 @@ static int xs_tcp_tls_handshake_sync(struct rpc_xprt *xprt)
 	return -EACCES;
 }
 
+/**
+ * xs_tcp_tls_handshake_async - Start a TLS handshake
+ * @xprt: transport on which to perform handshake
+ *
+ * Caller ensures there will be no other traffic on this transport.
+ *
+ * Return values:
+ *   %0: Handshake initiated; @xprt will be awoken when it's done.
+ *   Negative errno: handshake was not started.
+ */
+static int xs_tcp_tls_handshake_async(struct rpc_xprt *xprt)
+{
+	return -EACCES;
+}
+
 #endif /*CONFIG_TLS */
 
 /**
@@ -2845,6 +2900,7 @@ static const struct rpc_xprt_ops xs_tcp_ops = {
 	.disable_swap		= xs_disable_swap,
 	.inject_disconnect	= xs_inject_disconnect,
 	.tls_handshake_sync	= xs_tcp_tls_handshake_sync,
+	.tls_handshake_async	= xs_tcp_tls_handshake_async,
 #ifdef CONFIG_SUNRPC_BACKCHANNEL
 	.bc_setup		= xprt_setup_bc,
 	.bc_maxpayload		= xs_tcp_bc_maxpayload,