expose hostSupportsAppArmor()

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

pkg/apparmor/apparmor.go

@@ -0,0 +1,48 @@
+// +build apparmor,linux
+
+/*
+   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 apparmor
+
+import (
+	"io/ioutil"
+	"os"
+	"sync"
+)
+
+var (
+	appArmorSupported bool
+	checkAppArmor     sync.Once
+)
+
+// HostSupports returns true if apparmor is enabled for the host, if
+// apparmor_parser is enabled, and if we are not running docker-in-docker.
+//
+// It is a modified version of libcontainer/apparmor.IsEnabled(), which does not
+// check for apparmor_parser to be present, or if we're running docker-in-docker.
+func HostSupports() bool {
+	checkAppArmor.Do(func() {
+		// see https://github.com/docker/docker/commit/de191e86321f7d3136ff42ff75826b8107399497
+		if _, err := os.Stat("/sys/kernel/security/apparmor"); err == nil && os.Getenv("container") == "" {
+			if _, err = os.Stat("/sbin/apparmor_parser"); err == nil {
+				buf, err := ioutil.ReadFile("/sys/module/apparmor/parameters/enabled")
+				appArmorSupported = err == nil && len(buf) > 1 && buf[0] == 'Y'
+			}
+		}
+	})
+	return appArmorSupported
+}

pkg/apparmor/apparmor_unsupported.go

@@ -0,0 +1,24 @@
+// +build !apparmor !linux
+
+/*
+   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 apparmor
+
+//nolint: deadcode, unused
+func HostSupports() bool {
+	return false
+}