Remove hard coding of SELinux labels on systems without proper selinux policy.

If a system is configured for SELinux but does not know about docker or
containers, then we want the transitions of the policy to work.  Hard coding
the labels causes docker to break on older Fedora and RHEL systems

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)
Upstream-commit: 32ad78b0430079dcc53c245826a244afa2d9b6b6
Component: engine

components/engine/pkg/selinux/selinux.go

@@ -312,13 +312,10 @@ func GetLxcContexts() (processLabel string, fileLabel string) {
 	if !SelinuxEnabled() {
 		return "", ""
 	}
-	lxcPath := fmt.Sprintf("%s/content/lxc_contexts", GetSELinuxPolicyRoot())
-	fileLabel = "system_u:object_r:svirt_sandbox_file_t:s0"
-	processLabel = "system_u:system_r:svirt_lxc_net_t:s0"
-
+	lxcPath := fmt.Sprintf("%s/contexts/lxc_contexts", GetSELinuxPolicyRoot())
 	in, err := os.Open(lxcPath)
 	if err != nil {
-		goto exit
+		return "", ""
 	}
 	defer in.Close()
 
@@ -352,6 +349,11 @@ func GetLxcContexts() (processLabel string, fileLabel string) {
 			}
 		}
 	}
+
+	if processLabel == "" || fileLabel == "" {
+		return "", ""
+	}
+
 exit:
 	mcs := IntToMcs(os.Getpid(), 1024)
 	scon := NewContext(processLabel)