Update the vendoring of github.com/opencontainers/selinux

THis should make libpod easier to build on non linux platforms.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

Closes: #1000
Approved by: mheon

vendor/github.com/opencontainers/selinux/go-selinux/selinux.go

@@ -1,23 +1,9 @@
-// +build linux
+// +build !linux
 
 package selinux
 
 import (
-	"bufio"
-	"bytes"
-	"crypto/rand"
-	"encoding/binary"
 	"errors"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"os"
-	"path/filepath"
-	"regexp"
-	"strconv"
-	"strings"
-	"sync"
-	"syscall"
 )
 
 const (
@@ -27,270 +13,31 @@ const (
 	Permissive = 0
 	// Disabled constant to indicate SELinux is disabled
 	Disabled = -1
-
-	selinuxDir       = "/etc/selinux/"
-	selinuxConfig    = selinuxDir + "config"
-	selinuxfsMount   = "/sys/fs/selinux"
-	selinuxTypeTag   = "SELINUXTYPE"
-	selinuxTag       = "SELINUX"
-	xattrNameSelinux = "security.selinux"
-	stRdOnly         = 0x01
-	selinuxfsMagic   = 0xf97cff8c
 )
 
-type selinuxState struct {
-	enabledSet   bool
-	enabled      bool
-	selinuxfsSet bool
-	selinuxfs    string
-	mcsList      map[string]bool
-	sync.Mutex
-}
-
 var (
 	// ErrMCSAlreadyExists is returned when trying to allocate a duplicate MCS.
 	ErrMCSAlreadyExists = errors.New("MCS label already exists")
 	// ErrEmptyPath is returned when an empty path has been specified.
 	ErrEmptyPath = errors.New("empty path")
-
-	assignRegex = regexp.MustCompile(`^([^=]+)=(.*)$`)
-	roFileLabel string
-	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 verifySELinuxfsMount(mnt string) bool {
-	var buf syscall.Statfs_t
-	for {
-		err := syscall.Statfs(mnt, &buf)
-		if err == nil {
-			break
-		}
-		if err == syscall.EAGAIN {
-			continue
-		}
-		return false
-	}
-	if uint32(buf.Type) != uint32(selinuxfsMagic) {
-		return false
-	}
-	if (buf.Flags & stRdOnly) != 0 {
-		return false
-	}
-
-	return true
-}
-
-func findSELinuxfs() string {
-	// fast path: check the default mount first
-	if verifySELinuxfsMount(selinuxfsMount) {
-		return selinuxfsMount
-	}
-
-	// check if selinuxfs is available before going the slow path
-	fs, err := ioutil.ReadFile("/proc/filesystems")
-	if err != nil {
-		return ""
-	}
-	if !bytes.Contains(fs, []byte("\tselinuxfs\n")) {
-		return ""
-	}
-
-	// slow path: try to find among the mounts
-	f, err := os.Open("/proc/self/mountinfo")
-	if err != nil {
-		return ""
-	}
-	defer f.Close()
-
-	scanner := bufio.NewScanner(f)
-	for {
-		mnt := findSELinuxfsMount(scanner)
-		if mnt == "" { // error or not found
-			return ""
-		}
-		if verifySELinuxfsMount(mnt) {
-			return mnt
-		}
-	}
-}
-
-// findSELinuxfsMount returns a next selinuxfs mount point found,
-// if there is one, or an empty string in case of EOF or error.
-func findSELinuxfsMount(s *bufio.Scanner) string {
-	for s.Scan() {
-		txt := s.Text()
-		// The first field after - is fs type.
-		// Safe as spaces in mountpoints are encoded as \040
-		if !strings.Contains(txt, " - selinuxfs ") {
-			continue
-		}
-		const mPos = 5 // mount point is 5th field
-		fields := strings.SplitN(txt, " ", mPos+1)
-		if len(fields) < mPos+1 {
-			continue
-		}
-		return fields[mPos-1]
-	}
-
-	return ""
-}
-
-func (s *selinuxState) getSELinuxfs() string {
-	s.Lock()
-	selinuxfs := s.selinuxfs
-	selinuxfsSet := s.selinuxfsSet
-	s.Unlock()
-	if selinuxfsSet {
-		return selinuxfs
-	}
-
-	return s.setSELinuxfs(findSELinuxfs())
-}
-
-// 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) 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 filepath.Join(selinuxDir, readConfig(selinuxTypeTag))
-}
-
-func readCon(fpath string) (string, error) {
-	if fpath == "" {
-		return "", ErrEmptyPath
-	}
-
-	in, err := os.Open(fpath)
-	if err != nil {
-		return "", err
-	}
-	defer in.Close()
-
-	var retval string
-	if _, err := fmt.Fscanf(in, "%s", &retval); err != nil {
-		return "", err
-	}
-	return strings.Trim(retval, "\x00"), nil
+	return
 }
 
 // SetFileLabel sets the SELinux label for this path or returns an error.
 func SetFileLabel(fpath string, label string) error {
-	if fpath == "" {
-		return ErrEmptyPath
-	}
-	return lsetxattr(fpath, xattrNameSelinux, []byte(label), 0)
+	return nil
 }
 
 // FileLabel returns the SELinux label for this path or returns an error.
 func FileLabel(fpath string) (string, error) {
-	if fpath == "" {
-		return "", ErrEmptyPath
-	}
-
-	label, err := lgetxattr(fpath, 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
+	return "", nil
 }
 
 /*
@@ -298,7 +45,7 @@ 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)
+	return nil
 }
 
 /*
@@ -306,17 +53,17 @@ 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()))
+	return nil
 }
 
 // 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()))
+	return "", nil
 }
 
 // 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))
+	return "", nil
 }
 
 /*
@@ -324,26 +71,7 @@ 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(fpath string, val string) error {
-	if fpath == "" {
-		return ErrEmptyPath
-	}
-
-	out, err := os.OpenFile(fpath, 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
+	return "", nil
 }
 
 /*
@@ -352,29 +80,7 @@ the function then returns the context that the kernel will use.  This function
 can be used to see if two contexts are equivalent
 */
 func CanonicalizeContext(val string) (string, error) {
-	return readWriteCon(filepath.Join(getSelinuxMountPoint(), "context"), val)
-}
-
-func readWriteCon(fpath string, val string) (string, error) {
-	if fpath == "" {
-		return "", ErrEmptyPath
-	}
-	f, err := os.OpenFile(fpath, os.O_RDWR, 0)
-	if err != nil {
-		return "", err
-	}
-	defer f.Close()
-
-	_, err = f.Write([]byte(val))
-	if err != nil {
-		return "", err
-	}
-
-	var retval string
-	if _, err := fmt.Fscanf(f, "%s", &retval); err != nil {
-		return "", err
-	}
-	return strings.Trim(retval, "\x00"), nil
+	return "", nil
 }
 
 /*
@@ -382,61 +88,28 @@ 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)
+	return nil
 }
 
 // Get returns the Context as a string
 func (c Context) Get() string {
-	if c["level"] != "" {
-		return fmt.Sprintf("%s:%s:%s:%s", c["user"], c["role"], c["type"], c["level"])
-	}
-	return fmt.Sprintf("%s:%s:%s", c["user"], c["role"], c["type"])
+	return ""
 }
 
 // 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]
-		if len(con) > 3 {
-			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)
-		if len(con) > 3 {
-			mcsAdd(con[3])
-		}
-	}
-}
-
-func selinuxEnforcePath() string {
-	return fmt.Sprintf("%s/enforce", getSelinuxMountPoint())
+	return
 }
 
 // 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
+	return Disabled
 }
 
 /*
@@ -444,7 +117,7 @@ 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))
+	return nil
 }
 
 /*
@@ -453,101 +126,20 @@ 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 {
-	if mcs == "" {
-		return nil
-	}
-	state.Lock()
-	defer state.Unlock()
-	if state.mcsList[mcs] {
-		return ErrMCSAlreadyExists
-	}
-	state.mcsList[mcs] = true
-	return nil
-}
-
-func mcsDelete(mcs string) {
-	if mcs == "" {
-		return
-	}
-	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)
-		if len(con) > 3 {
-			mcsDelete(con[3])
-		}
-	}
+	return
 }
 
 // ROFileLabel returns the specified SELinux readonly file label
 func ROFileLabel() string {
-	return roFileLabel
+	return ""
 }
 
 /*
@@ -555,78 +147,12 @@ 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:
-	scon := NewContext(processLabel)
-	if scon["level"] != "" {
-		mcs := uniqMcs(1024)
-		scon["level"] = mcs
-		processLabel = scon.Get()
-		scon = NewContext(fileLabel)
-		scon["level"] = mcs
-		fileLabel = scon.Get()
-	}
-	return processLabel, fileLabel
+	return "", ""
 }
 
 // SecurityCheckContext validates that the SELinux label is understood by the kernel
 func SecurityCheckContext(val string) error {
-	return writeCon(fmt.Sprintf("%s/context", getSelinuxMountPoint()), val)
+	return nil
 }
 
 /*
@@ -634,84 +160,20 @@ CopyLevel returns a label with the MLS/MCS level from src label replaced 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 {
-	if fpath == "" {
-		return ErrEmptyPath
-	}
-
-	badPrefixes := []string{"/usr"}
-	for _, prefix := range badPrefixes {
-		if strings.HasPrefix(fpath, prefix) {
-			return fmt.Errorf("relabeling content in %s is not allowed", prefix)
-		}
-	}
-	return nil
+	return "", nil
 }
 
 // Chcon changes the `fpath` file object to the SELinux label `label`.
 // If `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 fpath == "" {
-		return ErrEmptyPath
-	}
-	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)
+	return nil
 }
 
 // DupSecOpt takes an SELinux process label and returns security options that
 // can be used to 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"] == "" {
-		return nil
-	}
-	dup := []string{"user:" + con["user"],
-		"role:" + con["role"],
-		"type:" + con["type"],
-	}
-
-	if con["level"] != "" {
-		dup = append(dup, "level:"+con["level"])
-	}
-
-	return dup
+	return nil
 }
 
 // DisableSecOpt returns a security opt that can be used to disable SELinux