winbindd: Fix a startup race with allocate_gid

If you try to allocate a GID before winbind is fully set up,
idmap_child_handle() is still NULL. Add the required
wb_parent_idmap_setup_send()/recv() to allocate_gid().

Bug: https://bugzilla.samba.org/show_bug.cgi?id=14678
RN: Fix a crash in winbind when allocate-gid is called early

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

1 files changed, 38 insertions, 5 deletions

diff --git a/source3/winbindd/winbindd_allocate_gid.c b/source3/winbindd/winbindd_allocate_gid.c
index 85aa1369473..2841d96e5f9 100644
--- a/source3/winbindd/winbindd_allocate_gid.c
+++ b/source3/winbindd/winbindd_allocate_gid.c
@@ -22,9 +22,11 @@
 #include "librpc/gen_ndr/ndr_winbind_c.h"
 
 struct winbindd_allocate_gid_state {
+	struct tevent_context *ev;
 	uint64_t gid;
 };
 
+static void winbindd_allocate_gid_initialized(struct tevent_req *subreq);
 static void winbindd_allocate_gid_done(struct tevent_req *subreq);
 
 struct tevent_req *winbindd_allocate_gid_send(TALLOC_CTX *mem_ctx,
@@ -34,25 +36,56 @@ struct tevent_req *winbindd_allocate_gid_send(TALLOC_CTX *mem_ctx,
 {
 	struct tevent_req *req, *subreq;
 	struct winbindd_allocate_gid_state *state;
-	struct dcerpc_binding_handle *child_binding_handle = NULL;
 
 	req = tevent_req_create(mem_ctx, &state,
 				struct winbindd_allocate_gid_state);
 	if (req == NULL) {
 		return NULL;
 	}
+	state->ev = ev;
 
 	DEBUG(3, ("allocate_gid\n"));
 
+	subreq = wb_parent_idmap_setup_send(state, ev);
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_req_set_callback(
+		subreq, winbindd_allocate_gid_initialized, req);
+	return req;
+}
+
+static void winbindd_allocate_gid_initialized(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct winbindd_allocate_gid_state *state = tevent_req_data(
+		req, struct winbindd_allocate_gid_state);
+	NTSTATUS status;
+	const struct wb_parent_idmap_config *cfg = NULL;
+	struct dcerpc_binding_handle *child_binding_handle = NULL;
+
+	status = wb_parent_idmap_setup_recv(subreq, &cfg);
+	TALLOC_FREE(subreq);
+	if (tevent_req_nterror(req, status)) {
+		return;
+	}
+	if (cfg->num_doms == 0) {
+		/*
+		 * idmap_tdb also returns UNSUCCESSFUL if a range is full
+		 */
+		tevent_req_nterror(req, NT_STATUS_UNSUCCESSFUL);
+		return;
+	}
+
 	child_binding_handle = idmap_child_handle();
 
-	subreq = dcerpc_wbint_AllocateGid_send(state, ev, child_binding_handle,
-					       &state->gid);
+	subreq = dcerpc_wbint_AllocateGid_send(
+		state, state->ev, child_binding_handle, &state->gid);
 	if (tevent_req_nomem(subreq, req)) {
-		return tevent_req_post(req, ev);
+		return;
 	}
 	tevent_req_set_callback(subreq, winbindd_allocate_gid_done, req);
-	return req;
 }
 
 static void winbindd_allocate_gid_done(struct tevent_req *subreq)