rxrpc: Simplify connect() implementation and simplify sendmsg() op

Simplify the RxRPC connect() implementation.  It will just note the
destination address it is given, and if a sendmsg() comes along with no
address, this will be assigned as the address.  No transport struct will be
held internally, which will allow us to remove this later.

Simplify sendmsg() also.  Whilst a call is active, userspace refers to it
by a private unique user ID specified in a control message.  When sendmsg()
sees a user ID that doesn't map to an extant call, it creates a new call
for that user ID and attempts to add it.  If, when we try to add it, the
user ID is now registered, we now reject the message with -EEXIST.  We
should never see this situation unless two threads are racing, trying to
create a call with the same ID - which would be an error.

It also isn't required to provide sendmsg() with an address - provided the
control message data holds a user ID that maps to a currently active call.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 63 insertions, 114 deletions

diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index 7840b8e7da80..38512a200db6 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -139,33 +139,33 @@ static int rxrpc_bind(struct socket *sock, struct sockaddr *saddr, int len)
 
 	lock_sock(&rx->sk);
 
-	if (rx->sk.sk_state != RXRPC_UNCONNECTED) {
+	if (rx->sk.sk_state != RXRPC_UNBOUND) {
 		ret = -EINVAL;
 		goto error_unlock;
 	}
 
 	memcpy(&rx->srx, srx, sizeof(rx->srx));
 
-	/* Find or create a local transport endpoint to use */
 	local = rxrpc_lookup_local(&rx->srx);
 	if (IS_ERR(local)) {
 		ret = PTR_ERR(local);
 		goto error_unlock;
 	}
 
-	rx->local = local;
-	if (srx->srx_service) {
+	if (rx->srx.srx_service) {
 		write_lock_bh(&local->services_lock);
 		list_for_each_entry(prx, &local->services, listen_link) {
-			if (prx->srx.srx_service == srx->srx_service)
+			if (prx->srx.srx_service == rx->srx.srx_service)
 				goto service_in_use;
 		}
 
+		rx->local = local;
 		list_add_tail(&rx->listen_link, &local->services);
 		write_unlock_bh(&local->services_lock);
 
 		rx->sk.sk_state = RXRPC_SERVER_BOUND;
 	} else {
+		rx->local = local;
 		rx->sk.sk_state = RXRPC_CLIENT_BOUND;
 	}
 
@@ -174,8 +174,9 @@ static int rxrpc_bind(struct socket *sock, struct sockaddr *saddr, int len)
 	return 0;
 
 service_in_use:
-	ret = -EADDRINUSE;
 	write_unlock_bh(&local->services_lock);
+	rxrpc_put_local(local);
+	ret = -EADDRINUSE;
 error_unlock:
 	release_sock(&rx->sk);
 error:
@@ -197,11 +198,11 @@ static int rxrpc_listen(struct socket *sock, int backlog)
 	lock_sock(&rx->sk);
 
 	switch (rx->sk.sk_state) {
-	case RXRPC_UNCONNECTED:
+	case RXRPC_UNBOUND:
 		ret = -EADDRNOTAVAIL;
 		break;
+	case RXRPC_CLIENT_UNBOUND:
 	case RXRPC_CLIENT_BOUND:
-	case RXRPC_CLIENT_CONNECTED:
 	default:
 		ret = -EBUSY;
 		break;
@@ -221,20 +222,18 @@ static int rxrpc_listen(struct socket *sock, int backlog)
 /*
  * find a transport by address
  */
-static struct rxrpc_transport *rxrpc_name_to_transport(struct socket *sock,
-						       struct sockaddr *addr,
-						       int addr_len, int flags,
-						       gfp_t gfp)
+struct rxrpc_transport *rxrpc_name_to_transport(struct rxrpc_sock *rx,
+						struct sockaddr *addr,
+						int addr_len, int flags,
+						gfp_t gfp)
 {
 	struct sockaddr_rxrpc *srx = (struct sockaddr_rxrpc *) addr;
 	struct rxrpc_transport *trans;
-	struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 	struct rxrpc_peer *peer;
 
 	_enter("%p,%p,%d,%d", rx, addr, addr_len, flags);
 
 	ASSERT(rx->local != NULL);
-	ASSERT(rx->sk.sk_state > RXRPC_UNCONNECTED);
 
 	if (rx->srx.transport_type != srx->transport_type)
 		return ERR_PTR(-ESOCKTNOSUPPORT);
@@ -256,7 +255,7 @@ static struct rxrpc_transport *rxrpc_name_to_transport(struct socket *sock,
 /**
  * rxrpc_kernel_begin_call - Allow a kernel service to begin a call
  * @sock: The socket on which to make the call
- * @srx: The address of the peer to contact (defaults to socket setting)
+ * @srx: The address of the peer to contact
  * @key: The security context to use (defaults to socket setting)
  * @user_call_ID: The ID to use
  *
@@ -282,25 +281,14 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock,
 
 	lock_sock(&rx->sk);
 
-	if (srx) {
-		trans = rxrpc_name_to_transport(sock, (struct sockaddr *) srx,
-						sizeof(*srx), 0, gfp);
-		if (IS_ERR(trans)) {
-			call = ERR_CAST(trans);
-			trans = NULL;
-			goto out_notrans;
-		}
-	} else {
-		trans = rx->trans;
-		if (!trans) {
-			call = ERR_PTR(-ENOTCONN);
-			goto out_notrans;
-		}
-		atomic_inc(&trans->usage);
+	trans = rxrpc_name_to_transport(rx, (struct sockaddr *)srx,
+					sizeof(*srx), 0, gfp);
+	if (IS_ERR(trans)) {
+		call = ERR_CAST(trans);
+		trans = NULL;
+		goto out_notrans;
 	}
 
-	if (!srx)
-		srx = &rx->srx;
 	if (!key)
 		key = rx->key;
 	if (key && !key->payload.data[0])
@@ -312,8 +300,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock,
 		goto out;
 	}
 
-	call = rxrpc_get_client_call(rx, trans, bundle, user_call_ID, true,
-				     gfp);
+	call = rxrpc_new_client_call(rx, trans, bundle, user_call_ID, gfp);
 	rxrpc_put_bundle(trans, bundle);
 out:
 	rxrpc_put_transport(trans);
@@ -369,11 +356,8 @@ EXPORT_SYMBOL(rxrpc_kernel_intercept_rx_messages);
 static int rxrpc_connect(struct socket *sock, struct sockaddr *addr,
 			 int addr_len, int flags)
 {
-	struct sockaddr_rxrpc *srx = (struct sockaddr_rxrpc *) addr;
-	struct sock *sk = sock->sk;
-	struct rxrpc_transport *trans;
-	struct rxrpc_local *local;
-	struct rxrpc_sock *rx = rxrpc_sk(sk);
+	struct sockaddr_rxrpc *srx = (struct sockaddr_rxrpc *)addr;
+	struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 	int ret;
 
 	_enter("%p,%p,%d,%d", rx, addr, addr_len, flags);
@@ -386,45 +370,28 @@ static int rxrpc_connect(struct socket *sock, struct sockaddr *addr,
 
 	lock_sock(&rx->sk);
 
+	ret = -EISCONN;
+	if (test_bit(RXRPC_SOCK_CONNECTED, &rx->flags))
+		goto error;
+
 	switch (rx->sk.sk_state) {
-	case RXRPC_UNCONNECTED:
-		/* find a local transport endpoint if we don't have one already */
-		ASSERTCMP(rx->local, ==, NULL);
-		rx->srx.srx_family = AF_RXRPC;
-		rx->srx.srx_service = 0;
-		rx->srx.transport_type = srx->transport_type;
-		rx->srx.transport_len = sizeof(sa_family_t);
-		rx->srx.transport.family = srx->transport.family;
-		local = rxrpc_lookup_local(&rx->srx);
-		if (IS_ERR(local)) {
-			release_sock(&rx->sk);
-			return PTR_ERR(local);
-		}
-		rx->local = local;
-		rx->sk.sk_state = RXRPC_CLIENT_BOUND;
+	case RXRPC_UNBOUND:
+		rx->sk.sk_state = RXRPC_CLIENT_UNBOUND;
+	case RXRPC_CLIENT_UNBOUND:
 	case RXRPC_CLIENT_BOUND:
 		break;
-	case RXRPC_CLIENT_CONNECTED:
-		release_sock(&rx->sk);
-		return -EISCONN;
 	default:
-		release_sock(&rx->sk);
-		return -EBUSY; /* server sockets can't connect as well */
-	}
-
-	trans = rxrpc_name_to_transport(sock, addr, addr_len, flags,
-					GFP_KERNEL);
-	if (IS_ERR(trans)) {
-		release_sock(&rx->sk);
-		_leave(" = %ld", PTR_ERR(trans));
-		return PTR_ERR(trans);
+		ret = -EBUSY;
+		goto error;
 	}
 
-	rx->trans = trans;
-	rx->sk.sk_state = RXRPC_CLIENT_CONNECTED;
+	rx->connect_srx = *srx;
+	set_bit(RXRPC_SOCK_CONNECTED, &rx->flags);
+	ret = 0;
 
+error:
 	release_sock(&rx->sk);
-	return 0;
+	return ret;
 }
 
 /*
@@ -438,7 +405,7 @@ static int rxrpc_connect(struct socket *sock, struct sockaddr *addr,
  */
 static int rxrpc_sendmsg(struct socket *sock, struct msghdr *m, size_t len)
 {
-	struct rxrpc_transport *trans;
+	struct rxrpc_local *local;
 	struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 	int ret;
 
@@ -455,48 +422,38 @@ static int rxrpc_sendmsg(struct socket *sock, struct msghdr *m, size_t len)
 		}
 	}
 
-	trans = NULL;
 	lock_sock(&rx->sk);
 
-	if (m->msg_name) {
-		ret = -EISCONN;
-		trans = rxrpc_name_to_transport(sock, m->msg_name,
-						m->msg_namelen, 0, GFP_KERNEL);
-		if (IS_ERR(trans)) {
-			ret = PTR_ERR(trans);
-			trans = NULL;
-			goto out;
-		}
-	} else {
-		trans = rx->trans;
-		if (trans)
-			atomic_inc(&trans->usage);
-	}
-
 	switch (rx->sk.sk_state) {
-	case RXRPC_SERVER_LISTENING:
-		if (!m->msg_name) {
-			ret = rxrpc_server_sendmsg(rx, m, len);
-			break;
+	case RXRPC_UNBOUND:
+		local = rxrpc_lookup_local(&rx->srx);
+		if (IS_ERR(local)) {
+			ret = PTR_ERR(local);
+			goto error_unlock;
 		}
-	case RXRPC_SERVER_BOUND:
+
+		rx->local = local;
+		rx->sk.sk_state = RXRPC_CLIENT_UNBOUND;
+		/* Fall through */
+
+	case RXRPC_CLIENT_UNBOUND:
 	case RXRPC_CLIENT_BOUND:
-		if (!m->msg_name) {
-			ret = -ENOTCONN;
-			break;
+		if (!m->msg_name &&
+		    test_bit(RXRPC_SOCK_CONNECTED, &rx->flags)) {
+			m->msg_name = &rx->connect_srx;
+			m->msg_namelen = sizeof(rx->connect_srx);
 		}
-	case RXRPC_CLIENT_CONNECTED:
-		ret = rxrpc_client_sendmsg(rx, trans, m, len);
+	case RXRPC_SERVER_BOUND:
+	case RXRPC_SERVER_LISTENING:
+		ret = rxrpc_do_sendmsg(rx, m, len);
 		break;
 	default:
-		ret = -ENOTCONN;
+		ret = -EINVAL;
 		break;
 	}
 
-out:
+error_unlock:
 	release_sock(&rx->sk);
-	if (trans)
-		rxrpc_put_transport(trans);
 	_leave(" = %d", ret);
 	return ret;
 }
@@ -523,7 +480,7 @@ static int rxrpc_setsockopt(struct socket *sock, int level, int optname,
 			if (optlen != 0)
 				goto error;
 			ret = -EISCONN;
-			if (rx->sk.sk_state != RXRPC_UNCONNECTED)
+			if (rx->sk.sk_state != RXRPC_UNBOUND)
 				goto error;
 			set_bit(RXRPC_SOCK_EXCLUSIVE_CONN, &rx->flags);
 			goto success;
@@ -533,7 +490,7 @@ static int rxrpc_setsockopt(struct socket *sock, int level, int optname,
 			if (rx->key)
 				goto error;
 			ret = -EISCONN;
-			if (rx->sk.sk_state != RXRPC_UNCONNECTED)
+			if (rx->sk.sk_state != RXRPC_UNBOUND)
 				goto error;
 			ret = rxrpc_request_key(rx, optval, optlen);
 			goto error;
@@ -543,7 +500,7 @@ static int rxrpc_setsockopt(struct socket *sock, int level, int optname,
 			if (rx->key)
 				goto error;
 			ret = -EISCONN;
-			if (rx->sk.sk_state != RXRPC_UNCONNECTED)
+			if (rx->sk.sk_state != RXRPC_UNBOUND)
 				goto error;
 			ret = rxrpc_server_keyring(rx, optval, optlen);
 			goto error;
@@ -553,7 +510,7 @@ static int rxrpc_setsockopt(struct socket *sock, int level, int optname,
 			if (optlen != sizeof(unsigned int))
 				goto error;
 			ret = -EISCONN;
-			if (rx->sk.sk_state != RXRPC_UNCONNECTED)
+			if (rx->sk.sk_state != RXRPC_UNBOUND)
 				goto error;
 			ret = get_user(min_sec_level,
 				       (unsigned int __user *) optval);
@@ -632,7 +589,7 @@ static int rxrpc_create(struct net *net, struct socket *sock, int protocol,
 		return -ENOMEM;
 
 	sock_init_data(sock, sk);
-	sk->sk_state		= RXRPC_UNCONNECTED;
+	sk->sk_state		= RXRPC_UNBOUND;
 	sk->sk_write_space	= rxrpc_write_space;
 	sk->sk_max_ack_backlog	= sysctl_rxrpc_max_qlen;
 	sk->sk_destruct		= rxrpc_sock_destructor;
@@ -705,14 +662,6 @@ static int rxrpc_release_sock(struct sock *sk)
 		rx->conn = NULL;
 	}
 
-	if (rx->bundle) {
-		rxrpc_put_bundle(rx->trans, rx->bundle);
-		rx->bundle = NULL;
-	}
-	if (rx->trans) {
-		rxrpc_put_transport(rx->trans);
-		rx->trans = NULL;
-	}
 	if (rx->local) {
 		rxrpc_put_local(rx->local);
 		rx->local = NULL;