update vendor

Signed-off-by: Jess Frazelle <acidburn@microsoft.com>

vendor/github.com/opencontainers/runc/libcontainer/system/linux.go

@@ -3,13 +3,12 @@
 package system
 
 import (
-	"bufio"
-	"fmt"
 	"os"
 	"os/exec"
 	"syscall" // only for exec
 	"unsafe"
 
+	"github.com/opencontainers/runc/libcontainer/user"
 	"golang.org/x/sys/unix"
 )
 
@@ -102,34 +101,43 @@ func Setctty() error {
 }
 
 // RunningInUserNS detects whether we are currently running in a user namespace.
-// Copied from github.com/lxc/lxd/shared/util.go
+// Originally copied from github.com/lxc/lxd/shared/util.go
 func RunningInUserNS() bool {
-	file, err := os.Open("/proc/self/uid_map")
+	uidmap, err := user.CurrentProcessUIDMap()
 	if err != nil {
 		// This kernel-provided file only exists if user namespaces are supported
 		return false
 	}
-	defer file.Close()
+	return UIDMapInUserNS(uidmap)
+}
 
-	buf := bufio.NewReader(file)
-	l, _, err := buf.ReadLine()
-	if err != nil {
-		return false
-	}
-
-	line := string(l)
-	var a, b, c int64
-	fmt.Sscanf(line, "%d %d %d", &a, &b, &c)
+func UIDMapInUserNS(uidmap []user.IDMap) bool {
 	/*
 	 * We assume we are in the initial user namespace if we have a full
 	 * range - 4294967295 uids starting at uid 0.
 	 */
-	if a == 0 && b == 0 && c == 4294967295 {
+	if len(uidmap) == 1 && uidmap[0].ID == 0 && uidmap[0].ParentID == 0 && uidmap[0].Count == 4294967295 {
 		return false
 	}
 	return true
 }
 
+// GetParentNSeuid returns the euid within the parent user namespace
+func GetParentNSeuid() int64 {
+	euid := int64(os.Geteuid())
+	uidmap, err := user.CurrentProcessUIDMap()
+	if err != nil {
+		// This kernel-provided file only exists if user namespaces are supported
+		return euid
+	}
+	for _, um := range uidmap {
+		if um.ID <= euid && euid <= um.ID+um.Count-1 {
+			return um.ParentID + euid - um.ID
+		}
+	}
+	return euid
+}
+
 // SetSubreaper sets the value i as the subreaper setting for the calling process
 func SetSubreaper(i int) error {
 	return unix.Prctl(PR_SET_CHILD_SUBREAPER, uintptr(i), 0, 0, 0)

vendor/github.com/opencontainers/runc/libcontainer/system/linux_test.go

@@ -0,0 +1,45 @@
+// +build linux
+
+package system
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/opencontainers/runc/libcontainer/user"
+)
+
+func TestUIDMapInUserNS(t *testing.T) {
+	cases := []struct {
+		s        string
+		expected bool
+	}{
+		{
+			s:        "         0          0 4294967295\n",
+			expected: false,
+		},
+		{
+			s:        "         0          0          1\n",
+			expected: true,
+		},
+		{
+			s:        "         0       1001          1\n         1     231072      65536\n",
+			expected: true,
+		},
+		{
+			// file exist but empty (the initial state when userns is created. see man 7 user_namespaces)
+			s:        "",
+			expected: true,
+		},
+	}
+	for _, c := range cases {
+		uidmap, err := user.ParseIDMap(strings.NewReader(c.s))
+		if err != nil {
+			t.Fatal(err)
+		}
+		actual := UIDMapInUserNS(uidmap)
+		if c.expected != actual {
+			t.Fatalf("expected %v, got %v for %q", c.expected, actual, c.s)
+		}
+	}
+}

vendor/github.com/opencontainers/runc/libcontainer/system/unsupported.go

@@ -2,8 +2,26 @@
 
 package system
 
+import (
+	"os"
+
+	"github.com/opencontainers/runc/libcontainer/user"
+)
+
 // RunningInUserNS is a stub for non-Linux systems
 // Always returns false
 func RunningInUserNS() bool {
 	return false
 }
+
+// UIDMapInUserNS is a stub for non-Linux systems
+// Always returns false
+func UIDMapInUserNS(uidmap []user.IDMap) bool {
+	return false
+}
+
+// GetParentNSeuid returns the euid within the parent user namespace
+// Always returns os.Geteuid on non-linux
+func GetParentNSeuid() int {
+	return os.Geteuid()
+}