s4-smb: serialise session setup operations

the mixture of async and sync code in gensec makes a EOF on a socket
during a session setup cause a crash. The simplest solution is to
stop processing events on the socket until the session setup is
complete.

2 files changed, 16 insertions, 0 deletions

diff --git a/source4/smb_server/smb/sesssetup.c b/source4/smb_server/smb/sesssetup.c
index 419a8cbf79..6b50bcb48e 100644
--- a/source4/smb_server/smb/sesssetup.c
+++ b/source4/smb_server/smb/sesssetup.c
@@ -31,6 +31,7 @@
 #include "smbd/service_stream.h"
 #include "param/param.h"
 #include "../lib/tsocket/tsocket.h"
+#include "lib/stream/packet.h"
 
 struct sesssetup_context {
 	struct auth_context *auth_context;
@@ -371,6 +372,7 @@ static void sesssetup_spnego_send(struct tevent_req *subreq)
 	DATA_BLOB session_key;
 
 	status = gensec_update_recv(subreq, req, &sess->spnego.out.secblob);
+	packet_recv_enable(req->smb_conn->packet);
 	TALLOC_FREE(subreq);
 	if (NT_STATUS_EQUAL(status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 		goto done;
@@ -488,6 +490,11 @@ static void sesssetup_spnego(struct smbsrv_request *req, union smb_sesssetup *se
 	if (!subreq) {
 		goto nomem;
 	}
+	/* disable receipt of more packets on this socket until we've
+	   finished with the session setup. This avoids a problem with
+	   crashes if we get EOF on the socket while processing a session
+	   setup */
+	packet_recv_disable(req->smb_conn->packet);
 	tevent_req_set_callback(subreq, sesssetup_spnego_send, s);
 
 	return;
diff --git a/source4/smb_server/smb2/sesssetup.c b/source4/smb_server/smb2/sesssetup.c
index 9b601d17c0..ddc161d80c 100644
--- a/source4/smb_server/smb2/sesssetup.c
+++ b/source4/smb_server/smb2/sesssetup.c
@@ -27,6 +27,7 @@
 #include "smb_server/smb_server.h"
 #include "smb_server/smb2/smb2_server.h"
 #include "smbd/service_stream.h"
+#include "lib/stream/packet.h"
 
 static void smb2srv_sesssetup_send(struct smb2srv_request *req, union smb_sesssetup *io)
 {
@@ -68,6 +69,8 @@ static void smb2srv_sesssetup_callback(struct tevent_req *subreq)
 	struct auth_session_info *session_info = NULL;
 	NTSTATUS status;
 
+	packet_recv_enable(req->smb_conn->packet);
+
 	status = gensec_update_recv(subreq, req, &io->smb2.out.secblob);
 	TALLOC_FREE(subreq);
 	if (NT_STATUS_EQUAL(status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
@@ -199,6 +202,12 @@ static void smb2srv_sesssetup_backend(struct smb2srv_request *req, union smb_ses
 		goto failed;
 	}
 
+	/* disable receipt of more packets on this socket until we've
+	   finished with the session setup. This avoids a problem with
+	   crashes if we get EOF on the socket while processing a session
+	   setup */
+	packet_recv_disable(req->smb_conn->packet);
+
 	return;
 nomem:
 	status = NT_STATUS_NO_MEMORY;