Gate FUSE behind a runsc flag

This change gates all FUSE commands (by gating /dev/fuse) behind a runsc
flag. In order to use FUSE commands, use the --fuse flag with the --vfs2
flag. Check if FUSE is enabled by running dmesg in the sandbox.

2 files changed, 13 insertions, 0 deletions

diff --git a/pkg/sentry/kernel/kernel.go b/pkg/sentry/kernel/kernel.go
index 2177b785a..240cd6fe0 100644
--- a/pkg/sentry/kernel/kernel.go
+++ b/pkg/sentry/kernel/kernel.go
@@ -81,6 +81,10 @@ import (
 // easy access everywhere. To be removed once VFS2 becomes the default.
 var VFS2Enabled = false
 
+// FUSEEnabled is set to true when FUSE is enabled. Added as a global for allow
+// easy access everywhere. To be removed once FUSE is completed.
+var FUSEEnabled = false
+
 // Kernel represents an emulated Linux kernel. It must be initialized by calling
 // Init() or LoadFrom().
 //
diff --git a/pkg/sentry/kernel/syslog.go b/pkg/sentry/kernel/syslog.go
index 4607cde2f..a83ce219c 100644
--- a/pkg/sentry/kernel/syslog.go
+++ b/pkg/sentry/kernel/syslog.go
@@ -98,6 +98,15 @@ func (s *syslog) Log() []byte {
 		s.msg = append(s.msg, []byte(fmt.Sprintf(format, time, selectMessage()))...)
 	}
 
+	if VFS2Enabled {
+		time += rand.Float64() / 2
+		s.msg = append(s.msg, []byte(fmt.Sprintf(format, time, "Setting up VFS2..."))...)
+		if FUSEEnabled {
+			time += rand.Float64() / 2
+			s.msg = append(s.msg, []byte(fmt.Sprintf(format, time, "Setting up FUSE..."))...)
+		}
+	}
+
 	time += rand.Float64() / 2
 	s.msg = append(s.msg, []byte(fmt.Sprintf(format, time, "Ready!"))...)