Add support & documentation to run containers with different file types

Udica is adding new features to allow users to define container process
and file types. This would allow us to setup trusted communications channels
between multiple security domains.  ContainerA -> ContainerB -> ContainerC

Add tests to make sure users can change file types

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

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

@@ -13,11 +13,12 @@ import (
 
 // Valid Label Options
 var validOptions = map[string]bool{
-	"disable": true,
-	"type":    true,
-	"user":    true,
-	"role":    true,
-	"level":   true,
+	"disable":  true,
+	"type":     true,
+	"filetype": true,
+	"user":     true,
+	"role":     true,
+	"level":    true,
 }
 
 var ErrIncompatibleLabel = fmt.Errorf("Bad SELinux option z and Z can not be used together")
@@ -51,13 +52,16 @@ func InitLabels(options []string) (plabel string, mlabel string, Err error) {
 				return "", mountLabel, 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)
+				return "", "", fmt.Errorf("Bad label option %q, valid options 'disable' or \n'user, role, level, type, filetype' 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])
+				return "", "", fmt.Errorf("Bad label option %q, valid options 'disable, user, role, level, type, filetype'", con[0])
 
 			}
+			if con[0] == "filetype" {
+				mcon["type"] = con[1]
+			}
 			pcon[con[0]] = con[1]
 			if con[0] == "level" || con[0] == "user" {
 				mcon[con[0]] = con[1]

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

@@ -18,6 +18,7 @@ import (
 	"strings"
 	"sync"
 	"syscall"
+	"golang.org/x/sys/unix"
 )
 
 const (
@@ -392,6 +393,14 @@ func SetExecLabel(label string) error {
 	return writeCon(fmt.Sprintf("/proc/self/task/%d/attr/exec", syscall.Gettid()), label)
 }
 
+/*
+SetTaskLabel sets the SELinux label for the current thread, or an error. 
+This requires the dyntransition permission.
+*/
+func SetTaskLabel(label string) error {
+	return writeCon(fmt.Sprintf("/proc/self/task/%d/attr/current", syscall.Gettid()), label)
+}
+
 // SetSocketLabel takes a process label and tells the kernel to assign the
 // label to the next socket that gets created
 func SetSocketLabel(label string) error {
@@ -403,6 +412,11 @@ func SocketLabel() (string, error) {
 	return readCon(fmt.Sprintf("/proc/self/task/%d/attr/sockcreate", syscall.Gettid()))
 }
 
+// PeerLabel retrieves the label of the client on the other side of a socket
+func PeerLabel(fd uintptr) (string, error) {
+	return unix.GetsockoptString(int(fd), syscall.SOL_SOCKET, syscall.SO_PEERSEC)
+}
+
 // SetKeyLabel takes a process label and tells the kernel to assign the
 // label to the next kernel keyring that gets created
 func SetKeyLabel(label string) error {

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

@@ -96,6 +96,14 @@ func SetExecLabel(label string) error {
 	return nil
 }
 
+/*
+SetTaskLabel sets the SELinux label for the current thread, or an error.
+This requires the dyntransition permission.
+*/
+func SetTaskLabel(label string) error {
+        return nil
+}
+
 /*
 SetSocketLabel sets the SELinux label that the kernel will use for any programs
 that are executed by the current process thread, or an error.
@@ -109,6 +117,11 @@ func SocketLabel() (string, error) {
 	return "", nil
 }
 
+// PeerLabel retrieves the label of the client on the other side of a socket
+func PeerLabel(fd uintptr) (string, error) {
+	return "", nil
+}
+
 // SetKeyLabel takes a process label and tells the kernel to assign the
 // label to the next kernel keyring that gets created
 func SetKeyLabel(label string) error {