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Merge pull request #157 from miaoyq/apply-selinux-opt

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Support selinux options/label
This commit is contained in:
Lantao Liu 2017-08-31 16:30:30 -07:00 committed by GitHub
commit 9c49624174
14 changed files with 1294 additions and 5 deletions
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5
cmd/cri-containerd/cri_containerd.go
View File

@ -20,6 +20,7 @@ import (
"os"
"github.com/golang/glog"
"github.com/opencontainers/selinux/go-selinux"
"github.com/spf13/pflag"
"github.com/kubernetes-incubator/cri-containerd/cmd/cri-containerd/options"
@ -37,6 +38,10 @@ func main() {
os.Exit(0)
}
if !o.EnableSelinux {
selinux.SetDisabled()
}
glog.V(2).Infof("Run cri-containerd grpc server on socket %q", o.SocketPath)
service, err := server.NewCRIContainerdService(
o.ContainerdEndpoint,

4
cmd/cri-containerd/options/options.go
View File

@ -46,6 +46,8 @@ type CRIContainerdOptions struct {
StreamServerPort string
// CgroupPath is the path for the cgroup that cri-containerd is placed in.
CgroupPath string
// EnableSelinux indicates to enable the selinux support
EnableSelinux bool
}
// NewCRIContainerdOptions returns a reference to CRIContainerdOptions
@ -74,6 +76,8 @@ func (c *CRIContainerdOptions) AddFlags(fs *pflag.FlagSet) {
fs.StringVar(&c.StreamServerPort, "stream-port",
"10010", "The port streaming server is listening on.")
fs.StringVar(&c.CgroupPath, "cgroup-path", "", "The cgroup that cri-containerd is part of. By default cri-containerd is not placed in a cgroup")
fs.BoolVar(&c.EnableSelinux, "selinux-enabled",
false, "Enable selinux support.")
}
// InitFlags must be called after adding all cli options flags are defined and

26
pkg/server/container_create.go
View File

@ -27,7 +27,9 @@ import (
"github.com/opencontainers/runc/libcontainer/devices"
runtimespec "github.com/opencontainers/runtime-spec/specs-go"
"github.com/opencontainers/runtime-tools/generate"
"github.com/opencontainers/selinux/go-selinux/label"
"golang.org/x/net/context"
"golang.org/x/sys/unix"
"k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
cio "github.com/kubernetes-incubator/cri-containerd/pkg/server/io"
@ -234,9 +236,17 @@ func (c *criContainerdService) generateContainerSpec(id string, sandboxPid uint3
}
securityContext := config.GetLinux().GetSecurityContext()
selinuxOpt := securityContext.GetSelinuxOptions()
processLabel, mountLabel, err := initSelinuxOpts(selinuxOpt)
if err != nil {
return nil, fmt.Errorf("failed to init selinux options %+v: %v", securityContext.GetSelinuxOptions(), err)
}
// Add extra mounts first so that CRI specified mounts can override.
addOCIBindMounts(&g, append(extraMounts, config.GetMounts()...))
mounts := append(extraMounts, config.GetMounts()...)
if err := addOCIBindMounts(&g, mounts, mountLabel); err != nil {
return nil, fmt.Errorf("failed to set OCI bind mounts %+v: %v", mounts, err)
}
if securityContext.GetPrivileged() {
if !sandboxConfig.GetLinux().GetSecurityContext().GetPrivileged() {
@ -259,6 +269,9 @@ func (c *criContainerdService) generateContainerSpec(id string, sandboxPid uint3
}
g.SetProcessSelinuxLabel(processLabel)
g.SetLinuxMountLabel(mountLabel)
// TODO: Figure out whether we should set no new privilege for sandbox container by default
g.SetProcessNoNewPrivileges(securityContext.GetNoNewPrivs())
@ -435,7 +448,7 @@ func setOCIDevicesPrivileged(g *generate.Generator) error {
// addOCIBindMounts adds bind mounts.
// TODO(random-liu): Figure out whether we need to change all CRI mounts to readonly when
// rootfs is readonly. (https://github.com/moby/moby/blob/master/daemon/oci_linux.go)
func addOCIBindMounts(g *generate.Generator, mounts []*runtime.Mount) {
func addOCIBindMounts(g *generate.Generator, mounts []*runtime.Mount, mountLabel string) error {
// Mount cgroup into the container as readonly, which inherits docker's behavior.
g.AddCgroupsMount("ro") // nolint: errcheck
for _, mount := range mounts {
@ -447,9 +460,16 @@ func addOCIBindMounts(g *generate.Generator, mounts []*runtime.Mount) {
} else {
options = append(options, "rw")
}
// TODO(random-liu): [P1] Apply selinux label
if mount.GetSelinuxRelabel() {
if err := label.Relabel(src, mountLabel, true); err != nil && err != unix.ENOTSUP {
return fmt.Errorf("relabel %q with %q failed: %v", src, mountLabel, err)
}
}
g.AddBindMount(src, dst, options)
}
return nil
}
func setOCIBindMountsPrivileged(g *generate.Generator) {

2
pkg/server/container_create_test.go
View File

@ -419,7 +419,7 @@ func TestPrivilegedBindMount(t *testing.T) {
t.Logf("TestCase %q", desc)
g := generate.New()
g.SetRootReadonly(test.readonlyRootFS)
addOCIBindMounts(&g, nil)
addOCIBindMounts(&g, nil, "")
if test.privileged {
setOCIBindMountsPrivileged(&g)
}

15
pkg/server/helpers.go
View File

@ -33,6 +33,8 @@ import (
"github.com/opencontainers/image-spec/identity"
imagespec "github.com/opencontainers/image-spec/specs-go/v1"
specs "github.com/opencontainers/runtime-spec/specs-go"
"github.com/opencontainers/selinux/go-selinux"
"github.com/opencontainers/selinux/go-selinux/label"
"golang.org/x/net/context"
"k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
@ -374,3 +376,16 @@ func getImageInfo(ctx context.Context, image containerd.Image, provider content.
config: ociimage.Config,
}, nil
}
func initSelinuxOpts(selinuxOpt *runtime.SELinuxOption) (string, string, error) {
if selinuxOpt == nil {
return "", "", nil
}
labelOpts := fmt.Sprintf("%s:%s:%s:%s",
selinuxOpt.GetUser(),
selinuxOpt.GetRole(),
selinuxOpt.GetRole(),
selinuxOpt.GetType())
return label.InitLabels(selinux.DupSecOpt(labelOpts))
}

71
pkg/server/helpers_selinux_test.go Normal file
View File

@ -0,0 +1,71 @@
// +build selinux
/*
Copyright 2017 The Kubernetes 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 server
import (
"testing"
"github.com/opencontainers/selinux/go-selinux"
"github.com/stretchr/testify/assert"
"k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
)
func TestInitSelinuxOpts(t *testing.T) {
if !selinux.GetEnabled() {
return
}
for desc, test := range map[string]struct {
selinuxOpt *runtime.SELinuxOption
processLabel string
mountLabels []string
}{
"testNullValue": {
selinuxOpt: nil,
processLabel: "",
mountLabels: []string{"", ""},
},
"testEmptyString": {
selinuxOpt: &runtime.SELinuxOption{
User: "",
Role: "",
Type: "",
Level: "",
},
processLabel: ":::",
mountLabels: []string{":object_r:container_file_t:", ":object_r:svirt_sandbox_file_t:"},
},
"testUser": {
selinuxOpt: &runtime.SELinuxOption{
User: "user_u",
Role: "user_r",
Type: "user_t",
Level: "s0:c1,c2",
},
processLabel: "user_u:user_r:user_t:s0:c1,c2",
mountLabels: []string{"user_u:object_r:container_file_t:s0:c1,c2", "user_u:object_r:svirt_sandbox_file_t:s0:c1,c2"},
},
} {
t.Logf("TestCase %q", desc)
processLabel, mountLabel, err := initSelinuxOpts(test.selinuxOpt)
assert.NoError(t, err)
assert.Equal(t, test.processLabel, processLabel)
assert.Contains(t, test.mountLabels, mountLabel)
}
}

8
pkg/server/sandbox_run.go
View File

@ -275,7 +275,13 @@ func (c *criContainerdService) generateSandboxContainerSpec(id string, config *r
g.RemoveLinuxNamespace(string(runtimespec.IPCNamespace)) // nolint: errcheck
}
// TODO(random-liu): [P1] Apply SeLinux options.
selinuxOpt := securityContext.GetSelinuxOptions()
processLabel, mountLabel, err := initSelinuxOpts(selinuxOpt)
if err != nil {
return nil, fmt.Errorf("failed to init selinux options %+v: %v", securityContext.GetSelinuxOptions(), err)
}
g.SetProcessSelinuxLabel(processLabel)
g.SetLinuxMountLabel(mountLabel)
supplementalGroups := securityContext.GetSupplementalGroups()
for _, group := range supplementalGroups {

1
vendor.conf
View File

@ -35,6 +35,7 @@ github.com/opencontainers/image-spec v1.0.0
github.com/opencontainers/runc e775f0fba3ea329b8b766451c892c41a3d49594d
github.com/opencontainers/runtime-spec v1.0.0
github.com/opencontainers/runtime-tools e29f3ca4eb806a582ee1a1864c7b0563bd64c19b
github.com/opencontainers/selinux 4a2974bf1ee960774ffd517717f1f45325af0206
github.com/pkg/errors v0.8.0
github.com/pmezard/go-difflib v1.0.0
github.com/PuerkitoBio/purell v1.0.0

201
vendor/github.com/opencontainers/selinux/LICENSE generated vendored Normal file
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@ -0,0 +1,201 @@
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7
vendor/github.com/opencontainers/selinux/README.md generated vendored Normal file
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@ -0,0 +1,7 @@
# selinux
[![GoDoc](https://godoc.org/github.com/opencontainers/selinux?status.svg)](https://godoc.org/github.com/opencontainers/selinux) [![Go Report Card](https://goreportcard.com/badge/github.com/opencontainers/selinux)](https://goreportcard.com/report/github.com/opencontainers/selinux) [![Build Status](https://travis-ci.org/opencontainers/selinux.svg?branch=master)](https://travis-ci.org/opencontainers/selinux)
Common SELinux package used across the container ecosystem.
Please see the [godoc](https://godoc.org/github.com/opencontainers/selinux) for more information.

84
vendor/github.com/opencontainers/selinux/go-selinux/label/label.go generated vendored Normal file
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@ -0,0 +1,84 @@
// +build !selinux !linux
package label
// InitLabels returns the process label and file labels to be used within
// the container. A list of options can be passed into this function to alter
// the labels.
func InitLabels(options []string) (string, string, error) {
return "", "", nil
}
func GetROMountLabel() string {
return ""
}
func GenLabels(options string) (string, string, error) {
return "", "", nil
}
func FormatMountLabel(src string, mountLabel string) string {
return src
}
func SetProcessLabel(processLabel string) error {
return nil
}
func GetFileLabel(path string) (string, error) {
return "", nil
}
func SetFileLabel(path string, fileLabel string) error {
return nil
}
func SetFileCreateLabel(fileLabel string) error {
return nil
}
func Relabel(path string, fileLabel string, shared bool) error {
return nil
}
func GetPidLabel(pid int) (string, error) {
return "", nil
}
func Init() {
}
func ReserveLabel(label string) error {
return nil
}
func ReleaseLabel(label string) error {
return nil
}
// DupSecOpt takes a process label and returns security options that
// can be used to set duplicate labels on future container processes
func DupSecOpt(src string) []string {
return nil
}
// DisableSecOpt returns a security opt that can disable labeling
// support for future container processes
func DisableSecOpt() []string {
return nil
}
// Validate checks that the label does not include unexpected options
func Validate(label string) error {
return nil
}
// RelabelNeeded checks whether the user requested a relabel
func RelabelNeeded(label string) bool {
return false
}
// IsShared checks that the label includes a "shared" mark
func IsShared(label string) bool {
return false
}

204
vendor/github.com/opencontainers/selinux/go-selinux/label/label_selinux.go generated vendored Normal file
View File

@ -0,0 +1,204 @@
// +build selinux,linux
package label
import (
"fmt"
"strings"
"github.com/opencontainers/selinux/go-selinux"
)
// Valid Label Options
var validOptions = map[string]bool{
"disable": true,
"type": true,
"user": true,
"role": true,
"level": true,
}
var ErrIncompatibleLabel = fmt.Errorf("Bad SELinux option z and Z can not be used together")
// InitLabels returns the process label and file labels to be used within
// the container. A list of options can be passed into this function to alter
// the labels. The labels returned will include a random MCS String, that is
// guaranteed to be unique.
func InitLabels(options []string) (string, string, error) {
if !selinux.GetEnabled() {
return "", "", nil
}
processLabel, mountLabel := selinux.ContainerLabels()
if processLabel != "" {
pcon := selinux.NewContext(processLabel)
mcon := selinux.NewContext(mountLabel)
for _, opt := range options {
if opt == "disable" {
return "", "", nil
}
if i := strings.Index(opt, ":"); i == -1 {
return "", "", fmt.Errorf("Bad label option %q, valid options 'disable' or \n'user, role, level, type' followed by ':' and a value", opt)
}
con := strings.SplitN(opt, ":", 2)
if !validOptions[con[0]] {
return "", "", fmt.Errorf("Bad label option %q, valid options 'disable, user, role, level, type'", con[0])
}
pcon[con[0]] = con[1]
if con[0] == "level" || con[0] == "user" {
mcon[con[0]] = con[1]
}
}
processLabel = pcon.Get()
mountLabel = mcon.Get()
}
return processLabel, mountLabel, nil
}
func ROMountLabel() string {
return selinux.ROFileLabel()
}
// DEPRECATED: The GenLabels function is only to be used during the transition to the official API.
func GenLabels(options string) (string, string, error) {
return InitLabels(strings.Fields(options))
}
// FormatMountLabel returns a string to be used by the mount command.
// The format of this string will be used to alter the labeling of the mountpoint.
// The string returned is suitable to be used as the options field of the mount command.
// If you need to have additional mount point options, you can pass them in as
// the first parameter. Second parameter is the label that you wish to apply
// to all content in the mount point.
func FormatMountLabel(src, mountLabel string) string {
if mountLabel != "" {
switch src {
case "":
src = fmt.Sprintf("context=%q", mountLabel)
default:
src = fmt.Sprintf("%s,context=%q", src, mountLabel)
}
}
return src
}
// SetProcessLabel takes a process label and tells the kernel to assign the
// label to the next program executed by the current process.
func SetProcessLabel(processLabel string) error {
if processLabel == "" {
return nil
}
return selinux.SetExecLabel(processLabel)
}
// ProcessLabel returns the process label that the kernel will assign
// to the next program executed by the current process. If "" is returned
// this indicates that the default labeling will happen for the process.
func ProcessLabel() (string, error) {
return selinux.ExecLabel()
}
// GetFileLabel returns the label for specified path
func FileLabel(path string) (string, error) {
return selinux.FileLabel(path)
}
// SetFileLabel modifies the "path" label to the specified file label
func SetFileLabel(path string, fileLabel string) error {
if selinux.GetEnabled() && fileLabel != "" {
return selinux.SetFileLabel(path, fileLabel)
}
return nil
}
// SetFileCreateLabel tells the kernel the label for all files to be created
func SetFileCreateLabel(fileLabel string) error {
if selinux.GetEnabled() {
return selinux.SetFSCreateLabel(fileLabel)
}
return nil
}
// Relabel changes the label of path to the filelabel string.
// It changes the MCS label to s0 if shared is true.
// This will allow all containers to share the content.
func Relabel(path string, fileLabel string, shared bool) error {
if !selinux.GetEnabled() {
return nil
}
if fileLabel == "" {
return nil
}
exclude_paths := map[string]bool{"/": true, "/usr": true, "/etc": true}
if exclude_paths[path] {
return fmt.Errorf("SELinux relabeling of %s is not allowed", path)
}
if shared {
c := selinux.NewContext(fileLabel)
c["level"] = "s0"
fileLabel = c.Get()
}
if err := selinux.Chcon(path, fileLabel, true); err != nil {
return err
}
return nil
}
// PidLabel will return the label of the process running with the specified pid
func PidLabel(pid int) (string, error) {
return selinux.PidLabel(pid)
}
// Init initialises the labeling system
func Init() {
selinux.GetEnabled()
}
// ReserveLabel will record the fact that the MCS label has already been used.
// This will prevent InitLabels from using the MCS label in a newly created
// container
func ReserveLabel(label string) error {
selinux.ReserveLabel(label)
return nil
}
// ReleaseLabel will remove the reservation of the MCS label.
// This will allow InitLabels to use the MCS label in a newly created
// containers
func ReleaseLabel(label string) error {
selinux.ReleaseLabel(label)
return nil
}
// DupSecOpt takes a process label and returns security options that
// can be used to set duplicate labels on future container processes
func DupSecOpt(src string) []string {
return selinux.DupSecOpt(src)
}
// DisableSecOpt returns a security opt that can disable labeling
// support for future container processes
func DisableSecOpt() []string {
return selinux.DisableSecOpt()
}
// Validate checks that the label does not include unexpected options
func Validate(label string) error {
if strings.Contains(label, "z") && strings.Contains(label, "Z") {
return ErrIncompatibleLabel
}
return nil
}
// RelabelNeeded checks whether the user requested a relabel
func RelabelNeeded(label string) bool {
return strings.Contains(label, "z") || strings.Contains(label, "Z")
}
// IsShared checks that the label includes a "shared" mark
func IsShared(label string) bool {
return strings.Contains(label, "z")
}

593
vendor/github.com/opencontainers/selinux/go-selinux/selinux.go generated vendored Normal file
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@ -0,0 +1,593 @@
// +build linux
package selinux
import (
"bufio"
"crypto/rand"
"encoding/binary"
"fmt"
"io"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"sync"
"syscall"
)
const (
// Enforcing constant indicate SELinux is in enforcing mode
Enforcing = 1
// Permissive constant to indicate SELinux is in permissive mode
Permissive = 0
// Disabled constant to indicate SELinux is disabled
Disabled = -1
selinuxDir = "/etc/selinux/"
selinuxConfig = selinuxDir + "config"
selinuxTypeTag = "SELINUXTYPE"
selinuxTag = "SELINUX"
selinuxPath = "/sys/fs/selinux"
xattrNameSelinux = "security.selinux"
stRdOnly = 0x01
)
type selinuxState struct {
enabledSet bool
enabled bool
selinuxfsSet bool
selinuxfs string
mcsList map[string]bool
sync.Mutex
}
var (
assignRegex = regexp.MustCompile(`^([^=]+)=(.*)$`)
state = selinuxState{
mcsList: make(map[string]bool),
}
)
// Context is a representation of the SELinux label broken into 4 parts
type Context map[string]string
func (s *selinuxState) setEnable(enabled bool) bool {
s.Lock()
defer s.Unlock()
s.enabledSet = true
s.enabled = enabled
return s.enabled
}
func (s *selinuxState) getEnabled() bool {
s.Lock()
enabled := s.enabled
enabledSet := s.enabledSet
s.Unlock()
if enabledSet {
return enabled
}
enabled = false
if fs := getSelinuxMountPoint(); fs != "" {
if con, _ := CurrentLabel(); con != "kernel" {
enabled = true
}
}
return s.setEnable(enabled)
}
// SetDisabled disables selinux support for the package
func SetDisabled() {
state.setEnable(false)
}
func (s *selinuxState) setSELinuxfs(selinuxfs string) string {
s.Lock()
defer s.Unlock()
s.selinuxfsSet = true
s.selinuxfs = selinuxfs
return s.selinuxfs
}
func (s *selinuxState) getSELinuxfs() string {
s.Lock()
selinuxfs := s.selinuxfs
selinuxfsSet := s.selinuxfsSet
s.Unlock()
if selinuxfsSet {
return selinuxfs
}
selinuxfs = ""
f, err := os.Open("/proc/self/mountinfo")
if err != nil {
return selinuxfs
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
txt := scanner.Text()
// Safe as mountinfo encodes mountpoints with spaces as \040.
sepIdx := strings.Index(txt, " - ")
if sepIdx == -1 {
continue
}
if !strings.Contains(txt[sepIdx:], "selinuxfs") {
continue
}
fields := strings.Split(txt, " ")
if len(fields) < 5 {
continue
}
selinuxfs = fields[4]
break
}
if selinuxfs != "" {
var buf syscall.Statfs_t
syscall.Statfs(selinuxfs, &buf)
if (buf.Flags & stRdOnly) == 1 {
selinuxfs = ""
}
}
return s.setSELinuxfs(selinuxfs)
}
// getSelinuxMountPoint returns the path to the mountpoint of an selinuxfs
// filesystem or an empty string if no mountpoint is found. Selinuxfs is
// a proc-like pseudo-filesystem that exposes the selinux policy API to
// processes. The existence of an selinuxfs mount is used to determine
// whether selinux is currently enabled or not.
func getSelinuxMountPoint() string {
return state.getSELinuxfs()
}
// GetEnabled returns whether selinux is currently enabled.
func GetEnabled() bool {
return state.getEnabled()
}
func readConfig(target string) (value string) {
var (
val, key string
bufin *bufio.Reader
)
in, err := os.Open(selinuxConfig)
if err != nil {
return ""
}
defer in.Close()
bufin = bufio.NewReader(in)
for done := false; !done; {
var line string
if line, err = bufin.ReadString('\n'); err != nil {
if err != io.EOF {
return ""
}
done = true
}
line = strings.TrimSpace(line)
if len(line) == 0 {
// Skip blank lines
continue
}
if line[0] == ';' || line[0] == '#' {
// Skip comments
continue
}
if groups := assignRegex.FindStringSubmatch(line); groups != nil {
key, val = strings.TrimSpace(groups[1]), strings.TrimSpace(groups[2])
if key == target {
return strings.Trim(val, "\"")
}
}
}
return ""
}
func getSELinuxPolicyRoot() string {
return selinuxDir + readConfig(selinuxTypeTag)
}
func readCon(name string) (string, error) {
var val string
in, err := os.Open(name)
if err != nil {
return "", err
}
defer in.Close()
_, err = fmt.Fscanf(in, "%s", &val)
return val, err
}
// SetFileLabel sets the SELinux label for this path or returns an error.
func SetFileLabel(path string, label string) error {
return lsetxattr(path, xattrNameSelinux, []byte(label), 0)
}
// FileLabel returns the SELinux label for this path or returns an error.
func FileLabel(path string) (string, error) {
label, err := lgetxattr(path, xattrNameSelinux)
if err != nil {
return "", err
}
// Trim the NUL byte at the end of the byte buffer, if present.
if len(label) > 0 && label[len(label)-1] == '\x00' {
label = label[:len(label)-1]
}
return string(label), nil
}
/*
SetFSCreateLabel tells kernel the label to create all file system objects
created by this task. Setting label="" to return to default.
*/
func SetFSCreateLabel(label string) error {
return writeCon(fmt.Sprintf("/proc/self/task/%d/attr/fscreate", syscall.Gettid()), label)
}
/*
FSCreateLabel returns the default label the kernel which the kernel is using
for file system objects created by this task. "" indicates default.
*/
func FSCreateLabel() (string, error) {
return readCon(fmt.Sprintf("/proc/self/task/%d/attr/fscreate", syscall.Gettid()))
}
// CurrentLabel returns the SELinux label of the current process thread, or an error.
func CurrentLabel() (string, error) {
return readCon(fmt.Sprintf("/proc/self/task/%d/attr/current", syscall.Gettid()))
}
// PidLabel returns the SELinux label of the given pid, or an error.
func PidLabel(pid int) (string, error) {
return readCon(fmt.Sprintf("/proc/%d/attr/current", pid))
}
/*
ExecLabel returns the SELinux label that the kernel will use for any programs
that are executed by the current process thread, or an error.
*/
func ExecLabel() (string, error) {
return readCon(fmt.Sprintf("/proc/self/task/%d/attr/exec", syscall.Gettid()))
}
func writeCon(name string, val string) error {
out, err := os.OpenFile(name, os.O_WRONLY, 0)
if err != nil {
return err
}
defer out.Close()
if val != "" {
_, err = out.Write([]byte(val))
} else {
_, err = out.Write(nil)
}
return err
}
/*
SetExecLabel sets the SELinux label that the kernel will use for any programs
that are executed by the current process thread, or an error.
*/
func SetExecLabel(label string) error {
return writeCon(fmt.Sprintf("/proc/self/task/%d/attr/exec", syscall.Gettid()), label)
}
// Get returns the Context as a string
func (c Context) Get() string {
return fmt.Sprintf("%s:%s:%s:%s", c["user"], c["role"], c["type"], c["level"])
}
// NewContext creates a new Context struct from the specified label
func NewContext(label string) Context {
c := make(Context)
if len(label) != 0 {
con := strings.SplitN(label, ":", 4)
c["user"] = con[0]
c["role"] = con[1]
c["type"] = con[2]
c["level"] = con[3]
}
return c
}
// ReserveLabel reserves the MLS/MCS level component of the specified label
func ReserveLabel(label string) {
if len(label) != 0 {
con := strings.SplitN(label, ":", 4)
mcsAdd(con[3])
}
}
func selinuxEnforcePath() string {
return fmt.Sprintf("%s/enforce", selinuxPath)
}
// EnforceMode returns the current SELinux mode Enforcing, Permissive, Disabled
func EnforceMode() int {
var enforce int
enforceS, err := readCon(selinuxEnforcePath())
if err != nil {
return -1
}
enforce, err = strconv.Atoi(string(enforceS))
if err != nil {
return -1
}
return enforce
}
/*
SetEnforceMode sets the current SELinux mode Enforcing, Permissive.
Disabled is not valid, since this needs to be set at boot time.
*/
func SetEnforceMode(mode int) error {
return writeCon(selinuxEnforcePath(), fmt.Sprintf("%d", mode))
}
/*
DefaultEnforceMode returns the systems default SELinux mode Enforcing,
Permissive or Disabled. Note this is is just the default at boot time.
EnforceMode tells you the systems current mode.
*/
func DefaultEnforceMode() int {
switch readConfig(selinuxTag) {
case "enforcing":
return Enforcing
case "permissive":
return Permissive
}
return Disabled
}
func mcsAdd(mcs string) error {
state.Lock()
defer state.Unlock()
if state.mcsList[mcs] {
return fmt.Errorf("MCS Label already exists")
}
state.mcsList[mcs] = true
return nil
}
func mcsDelete(mcs string) {
state.Lock()
defer state.Unlock()
state.mcsList[mcs] = false
}
func intToMcs(id int, catRange uint32) string {
var (
SETSIZE = int(catRange)
TIER = SETSIZE
ORD = id
)
if id < 1 || id > 523776 {
return ""
}
for ORD > TIER {
ORD = ORD - TIER
TIER--
}
TIER = SETSIZE - TIER
ORD = ORD + TIER
return fmt.Sprintf("s0:c%d,c%d", TIER, ORD)
}
func uniqMcs(catRange uint32) string {
var (
n uint32
c1, c2 uint32
mcs string
)
for {
binary.Read(rand.Reader, binary.LittleEndian, &n)
c1 = n % catRange
binary.Read(rand.Reader, binary.LittleEndian, &n)
c2 = n % catRange
if c1 == c2 {
continue
} else {
if c1 > c2 {
c1, c2 = c2, c1
}
}
mcs = fmt.Sprintf("s0:c%d,c%d", c1, c2)
if err := mcsAdd(mcs); err != nil {
continue
}
break
}
return mcs
}
/*
ReleaseLabel will unreserve the MLS/MCS Level field of the specified label.
Allowing it to be used by another process.
*/
func ReleaseLabel(label string) {
if len(label) != 0 {
con := strings.SplitN(label, ":", 4)
mcsDelete(con[3])
}
}
var roFileLabel string
// ROFileLabel returns the specified SELinux readonly file label
func ROFileLabel() (fileLabel string) {
return roFileLabel
}
/*
ContainerLabels returns an allocated processLabel and fileLabel to be used for
container labeling by the calling process.
*/
func ContainerLabels() (processLabel string, fileLabel string) {
var (
val, key string
bufin *bufio.Reader
)
if !GetEnabled() {
return "", ""
}
lxcPath := fmt.Sprintf("%s/contexts/lxc_contexts", getSELinuxPolicyRoot())
in, err := os.Open(lxcPath)
if err != nil {
return "", ""
}
defer in.Close()
bufin = bufio.NewReader(in)
for done := false; !done; {
var line string
if line, err = bufin.ReadString('\n'); err != nil {
if err == io.EOF {
done = true
} else {
goto exit
}
}
line = strings.TrimSpace(line)
if len(line) == 0 {
// Skip blank lines
continue
}
if line[0] == ';' || line[0] == '#' {
// Skip comments
continue
}
if groups := assignRegex.FindStringSubmatch(line); groups != nil {
key, val = strings.TrimSpace(groups[1]), strings.TrimSpace(groups[2])
if key == "process" {
processLabel = strings.Trim(val, "\"")
}
if key == "file" {
fileLabel = strings.Trim(val, "\"")
}
if key == "ro_file" {
roFileLabel = strings.Trim(val, "\"")
}
}
}
if processLabel == "" || fileLabel == "" {
return "", ""
}
if roFileLabel == "" {
roFileLabel = fileLabel
}
exit:
mcs := uniqMcs(1024)
scon := NewContext(processLabel)
scon["level"] = mcs
processLabel = scon.Get()
scon = NewContext(fileLabel)
scon["level"] = mcs
fileLabel = scon.Get()
return processLabel, fileLabel
}
// SecurityCheckContext validates that the SELinux label is understood by the kernel
func SecurityCheckContext(val string) error {
return writeCon(fmt.Sprintf("%s.context", selinuxPath), val)
}
/*
CopyLevel returns a label with the MLS/MCS level from src label replaces on
the dest label.
*/
func CopyLevel(src, dest string) (string, error) {
if src == "" {
return "", nil
}
if err := SecurityCheckContext(src); err != nil {
return "", err
}
if err := SecurityCheckContext(dest); err != nil {
return "", err
}
scon := NewContext(src)
tcon := NewContext(dest)
mcsDelete(tcon["level"])
mcsAdd(scon["level"])
tcon["level"] = scon["level"]
return tcon.Get(), nil
}
// Prevent users from relabing system files
func badPrefix(fpath string) error {
var badprefixes = []string{"/usr"}
for _, prefix := range badprefixes {
if fpath == prefix || strings.HasPrefix(fpath, fmt.Sprintf("%s/", prefix)) {
return fmt.Errorf("relabeling content in %s is not allowed", prefix)
}
}
return nil
}
// Chcon changes the fpath file object to the SELinux label label.
// If the fpath is a directory and recurse is true Chcon will walk the
// directory tree setting the label
func Chcon(fpath string, label string, recurse bool) error {
if label == "" {
return nil
}
if err := badPrefix(fpath); err != nil {
return err
}
callback := func(p string, info os.FileInfo, err error) error {
return SetFileLabel(p, label)
}
if recurse {
return filepath.Walk(fpath, callback)
}
return SetFileLabel(fpath, label)
}
// DupSecOpt takes an SELinux process label and returns security options that
// can will set the SELinux Type and Level for future container processes
func DupSecOpt(src string) []string {
if src == "" {
return nil
}
con := NewContext(src)
if con["user"] == "" ||
con["role"] == "" ||
con["type"] == "" ||
con["level"] == "" {
return nil
}
return []string{"user:" + con["user"],
"role:" + con["role"],
"type:" + con["type"],
"level:" + con["level"]}
}
// DisableSecOpt returns a security opt that can be used to disabling SELinux
// labeling support for future container processes
func DisableSecOpt() []string {
return []string{"disable"}
}

78
vendor/github.com/opencontainers/selinux/go-selinux/xattrs.go generated vendored Normal file
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@ -0,0 +1,78 @@
// +build linux
package selinux
import (
"syscall"
"unsafe"
)
var _zero uintptr
// Returns a []byte slice if the xattr is set and nil otherwise
// Requires path and its attribute as arguments
func lgetxattr(path string, attr string) ([]byte, error) {
var sz int
pathBytes, err := syscall.BytePtrFromString(path)
if err != nil {
return nil, err
}
attrBytes, err := syscall.BytePtrFromString(attr)
if err != nil {
return nil, err
}
// Start with a 128 length byte array
sz = 128
dest := make([]byte, sz)
destBytes := unsafe.Pointer(&dest[0])
_sz, _, errno := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
switch {
case errno == syscall.ENODATA:
return nil, errno
case errno == syscall.ENOTSUP:
return nil, errno
case errno == syscall.ERANGE:
// 128 byte array might just not be good enough,
// A dummy buffer is used ``uintptr(0)`` to get real size
// of the xattrs on disk
_sz, _, errno = syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(unsafe.Pointer(nil)), uintptr(0), 0, 0)
sz = int(_sz)
if sz < 0 {
return nil, errno
}
dest = make([]byte, sz)
destBytes := unsafe.Pointer(&dest[0])
_sz, _, errno = syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
if errno != 0 {
return nil, errno
}
case errno != 0:
return nil, errno
}
sz = int(_sz)
return dest[:sz], nil
}
func lsetxattr(path string, attr string, data []byte, flags int) error {
pathBytes, err := syscall.BytePtrFromString(path)
if err != nil {
return err
}
attrBytes, err := syscall.BytePtrFromString(attr)
if err != nil {
return err
}
var dataBytes unsafe.Pointer
if len(data) > 0 {
dataBytes = unsafe.Pointer(&data[0])
} else {
dataBytes = unsafe.Pointer(&_zero)
}
_, _, errno := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(dataBytes), uintptr(len(data)), uintptr(flags), 0)
if errno != 0 {
return errno
}
return nil
}