Handle KVM based runtimes with selinux

Signed-off-by: Michael Crosby <michael@thepasture.io>

pkg/seutil/seutil.go

@@ -0,0 +1,71 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package seutil
+
+import (
+	"bufio"
+	"os"
+
+	"github.com/opencontainers/selinux/go-selinux"
+)
+
+var seTypes map[string]struct{}
+
+const typePath = "/etc/selinux/targeted/contexts/customizable_types"
+
+func init() {
+	seTypes = make(map[string]struct{})
+	if !selinux.GetEnabled() {
+		return
+	}
+	f, err := os.Open(typePath)
+	if err != nil {
+		return
+	}
+	defer f.Close()
+	s := bufio.NewScanner(f)
+	for s.Scan() {
+		seTypes[s.Text()] = struct{}{}
+	}
+}
+
+// HasType returns true if the underlying system has the
+// provided selinux type enabled.
+func HasType(name string) bool {
+	_, ok := seTypes[name]
+	return ok
+}
+
+// ChangeToKVM process label
+func ChangeToKVM(l string) (string, error) {
+	if l == "" || !selinux.GetEnabled() {
+		return "", nil
+	}
+	proc, _ := selinux.KVMContainerLabels()
+	selinux.ReleaseLabel(proc)
+
+	current, err := selinux.NewContext(l)
+	if err != nil {
+		return "", err
+	}
+	next, err := selinux.NewContext(proc)
+	if err != nil {
+		return "", err
+	}
+	current["type"] = next["type"]
+	return current.Get(), nil
+}