podman/libpod: add default AppArmor profile

Make users of libpod more secure by adding the libpod/apparmor package
to load a pre-defined AppArmor profile.  Large chunks of libpod/apparmor
come from github.com/moby/moby.

Also check if a specified AppArmor profile is actually loaded and throw
an error if necessary.

The default profile is loaded only on Linux builds with the `apparmor`
buildtag enabled.

Signed-off-by: Valentin Rothberg <vrothberg@suse.com>

Closes: #1063
Approved by: rhatdan

1 files changed, 110 insertions, 0 deletions

diff --git a/pkg/apparmor/apparmor_linux.go b/pkg/apparmor/apparmor_linux.go
new file mode 100644
index 000000000..6e8b7f312
--- /dev/null
+++ b/pkg/apparmor/apparmor_linux.go
@@ -0,0 +1,110 @@
+// +build linux,apparmor
+
+package apparmor
+
+import (
+	"bufio"
+	"io"
+	"io/ioutil"
+	"os"
+	"path"
+	"strings"
+	"text/template"
+)
+
+// profileData holds information about the given profile for generation.
+type profileData struct {
+	// Name is profile name.
+	Name string
+	// Imports defines the apparmor functions to import, before defining the profile.
+	Imports []string
+	// InnerImports defines the apparmor functions to import in the profile.
+	InnerImports []string
+	// Version is the {major, minor, patch} version of apparmor_parser as a single number.
+	Version int
+}
+
+// generateDefault creates an apparmor profile from ProfileData.
+func (p *profileData) generateDefault(out io.Writer) error {
+	compiled, err := template.New("apparmor_profile").Parse(libpodProfileTemplate)
+	if err != nil {
+		return err
+	}
+
+	if macroExists("tunables/global") {
+		p.Imports = append(p.Imports, "#include <tunables/global>")
+	} else {
+		p.Imports = append(p.Imports, "@{PROC}=/proc/")
+	}
+
+	if macroExists("abstractions/base") {
+		p.InnerImports = append(p.InnerImports, "#include <abstractions/base>")
+	}
+
+	ver, err := getVersion()
+	if err != nil {
+		return err
+	}
+	p.Version = ver
+
+	return compiled.Execute(out, p)
+}
+
+// macrosExists checks if the passed macro exists.
+func macroExists(m string) bool {
+	_, err := os.Stat(path.Join(profileDirectory, m))
+	return err == nil
+}
+
+// InstallDefault generates a default profile in a temp directory determined by
+// os.TempDir(), then loads the profile into the kernel using 'apparmor_parser'.
+func InstallDefault(name string) error {
+	p := profileData{
+		Name: name,
+	}
+
+	// Install to a temporary directory.
+	f, err := ioutil.TempFile("", name)
+	if err != nil {
+		return err
+	}
+	profilePath := f.Name()
+
+	defer f.Close()
+	defer os.Remove(profilePath)
+
+	if err := p.generateDefault(f); err != nil {
+		return err
+	}
+
+	return loadProfile(profilePath)
+}
+
+// IsLoaded checks if a profile with the given name has been loaded into the
+// kernel.
+func IsLoaded(name string) (bool, error) {
+	file, err := os.Open("/sys/kernel/security/apparmor/profiles")
+	if err != nil {
+		if os.IsNotExist(err) {
+			return false, nil
+		}
+		return false, err
+	}
+	defer file.Close()
+
+	r := bufio.NewReader(file)
+	for {
+		p, err := r.ReadString('\n')
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return false, err
+		}
+		if strings.HasPrefix(p, name+" ") {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}