Allow piping VM failure reason

Allow crosvm to write a VM failure reason to virtualizationservice via the pipe provided.

Fixes this denial: avc: denied { write } for path="pipe:[95872]"
dev="pipefs" ino=95872 scontext=u:r:crosvm:s0
tcontext=u:r:virtualizationservice:s0 tclass=fifo_file

Bug: 220071963
Test: Run VM, no denial.
Change-Id: I3beedc5e715aa33209d3df0cae05f45f31e79e66
diff --git a/private/crosvm.te b/private/crosvm.te
index 25d3309..26b1df3 100644
--- a/private/crosvm.te
+++ b/private/crosvm.te
@@ -19,6 +19,9 @@
 # Let crosvm receive file descriptors from VirtualizationService.
 allow crosvm virtualizationservice:fd use;
 
+# Allow sending VirtualizationService the failure reason from the VM via pipe.
+allow crosvm virtualizationservice:fifo_file write;
+
 # Let crosvm read the composite disk images (virtualizationservice_data_file), APEXes
 # (staging_data_file), APKs (apk_data_file and shell_data_file where the latter is for test apks in
 # /data/local/tmp), and instance.img (app_data_file). Note that the open permission is not given as