Add default apparmor profile generation

This adds default apparmor profile generation to the containerd client
so that profiles can be generated with a SpecOpt

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

apparmor.go

@@ -1,18 +0,0 @@
-// +build linux
-
-package containerd
-
-import (
-	"context"
-
-	"github.com/containerd/containerd/containers"
-	specs "github.com/opencontainers/runtime-spec/specs-go"
-)
-
-// WithApparmor sets the provided apparmor profile to the spec
-func WithApparmorProfile(profile string) SpecOpts {
-	return func(_ context.Context, _ *Client, _ *containers.Container, s *specs.Spec) error {
-		s.Process.ApparmorProfile = profile
-		return nil
-	}
-}

contrib/apparmor/apparmor.go

@@ -0,0 +1,57 @@
+// +build linux
+
+package apparmor
+
+import (
+	"context"
+	"io/ioutil"
+	"os"
+
+	"github.com/containerd/containerd"
+	"github.com/containerd/containerd/containers"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+)
+
+// WithProfile sets the provided apparmor profile to the spec
+func WithProfile(profile string) containerd.SpecOpts {
+	return func(_ context.Context, _ *containerd.Client, _ *containers.Container, s *specs.Spec) error {
+		s.Process.ApparmorProfile = profile
+		return nil
+	}
+}
+
+// WithDefaultProfile will generate a default apparmor profile under the provided name
+// for the container.  It is only generated if a profile under that name does not exist.
+func WithDefaultProfile(name string) containerd.SpecOpts {
+	return func(_ context.Context, _ *containerd.Client, _ *containers.Container, s *specs.Spec) error {
+		yes, err := isLoaded(name)
+		if err != nil {
+			return err
+		}
+		if yes {
+			s.Process.ApparmorProfile = name
+			return nil
+		}
+		p, err := loadData(name)
+		if err != nil {
+			return err
+		}
+		f, err := ioutil.TempFile("", p.Name)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		path := f.Name()
+		defer os.Remove(path)
+
+		if err := generate(p, f); err != nil {
+			return err
+		}
+		if err := load(path); err != nil {
+			return errors.Wrapf(err, "load apparmor profile %s", path)
+		}
+		s.Process.ApparmorProfile = name
+		return nil
+	}
+}

contrib/apparmor/template.go

@@ -0,0 +1,193 @@
+// +build linux
+
+package apparmor
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"path"
+	"strconv"
+	"strings"
+	"text/template"
+
+	"github.com/pkg/errors"
+)
+
+const dir = "/etc/apparmor.d"
+
+const defaultTemplate = `
+{{range $value := .Imports}}
+{{$value}}
+{{end}}
+
+profile {{.Name}} flags=(attach_disconnected,mediate_deleted) {
+{{range $value := .InnerImports}}
+  {{$value}}
+{{end}}
+
+  network,
+  capability,
+  file,
+  umount,
+
+  deny @{PROC}/* w,   # deny write for all files directly in /proc (not in a subdir)
+  # deny write to files not in /proc/<number>/** or /proc/sys/**
+  deny @{PROC}/{[^1-9],[^1-9][^0-9],[^1-9s][^0-9y][^0-9s],[^1-9][^0-9][^0-9][^0-9]*}/** w,
+  deny @{PROC}/sys/[^k]** w,  # deny /proc/sys except /proc/sys/k* (effectively /proc/sys/kernel)
+  deny @{PROC}/sys/kernel/{?,??,[^s][^h][^m]**} w,  # deny everything except shm* in /proc/sys/kernel/
+  deny @{PROC}/sysrq-trigger rwklx,
+  deny @{PROC}/mem rwklx,
+  deny @{PROC}/kmem rwklx,
+  deny @{PROC}/kcore rwklx,
+
+  deny mount,
+
+  deny /sys/[^f]*/** wklx,
+  deny /sys/f[^s]*/** wklx,
+  deny /sys/fs/[^c]*/** wklx,
+  deny /sys/fs/c[^g]*/** wklx,
+  deny /sys/fs/cg[^r]*/** wklx,
+  deny /sys/firmware/** rwklx,
+  deny /sys/kernel/security/** rwklx,
+
+{{if ge .Version 208095}}
+  ptrace (trace,read) peer={{.Name}},
+{{end}}
+}
+`
+
+type data struct {
+	Name         string
+	Imports      []string
+	InnerImports []string
+	Version      int
+}
+
+func loadData(name string) (*data, error) {
+	p := data{
+		Name: name,
+	}
+
+	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 nil, errors.Wrap(err, "get apparmor_parser version")
+	}
+	p.Version = ver
+	return &p, nil
+}
+
+func generate(p *data, o io.Writer) error {
+	t, err := template.New("apparmor_profile").Parse(defaultTemplate)
+	if err != nil {
+		return err
+	}
+	return t.Execute(o, p)
+}
+
+func load(path string) error {
+	out, err := aaParser("-Kr", path)
+	if err != nil {
+		return errors.Errorf("%s: %s", err, out)
+	}
+	return nil
+}
+
+// macrosExists checks if the passed macro exists.
+func macroExists(m string) bool {
+	_, err := os.Stat(path.Join(dir, m))
+	return err == nil
+}
+
+func aaParser(args ...string) (string, error) {
+	out, err := exec.Command("apparmor_parser", args...).CombinedOutput()
+	if err != nil {
+		return "", err
+	}
+	return string(out), nil
+}
+
+func getVersion() (int, error) {
+	out, err := aaParser("--version")
+	if err != nil {
+		return -1, err
+	}
+	return parseVersion(out)
+}
+
+// parseVersion takes the output from `apparmor_parser --version` and returns
+// a representation of the {major, minor, patch} version as a single number of
+// the form MMmmPPP {major, minor, patch}.
+func parseVersion(output string) (int, error) {
+	// output is in the form of the following:
+	// AppArmor parser version 2.9.1
+	// Copyright (C) 1999-2008 Novell Inc.
+	// Copyright 2009-2012 Canonical Ltd.
+
+	lines := strings.SplitN(output, "\n", 2)
+	words := strings.Split(lines[0], " ")
+	version := words[len(words)-1]
+
+	// split by major minor version
+	v := strings.Split(version, ".")
+	if len(v) == 0 || len(v) > 3 {
+		return -1, fmt.Errorf("parsing version failed for output: `%s`", output)
+	}
+
+	// Default the versions to 0.
+	var majorVersion, minorVersion, patchLevel int
+
+	majorVersion, err := strconv.Atoi(v[0])
+	if err != nil {
+		return -1, err
+	}
+
+	if len(v) > 1 {
+		minorVersion, err = strconv.Atoi(v[1])
+		if err != nil {
+			return -1, err
+		}
+	}
+	if len(v) > 2 {
+		patchLevel, err = strconv.Atoi(v[2])
+		if err != nil {
+			return -1, err
+		}
+	}
+
+	// major*10^5 + minor*10^3 + patch*10^0
+	numericVersion := majorVersion*1e5 + minorVersion*1e3 + patchLevel
+	return numericVersion, nil
+}
+
+func isLoaded(name string) (bool, error) {
+	f, err := os.Open("/sys/kernel/security/apparmor/profiles")
+	if err != nil {
+		return false, err
+	}
+	defer f.Close()
+	r := bufio.NewReader(f)
+	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
+}