Merge pull request hashicorp#5728 from hashicorp/restore-08-caps

drivers/exec: Restore 0.8 capabilities

Author: Mahmood Ali

drivers/exec/driver_test.go

@@ -475,6 +475,7 @@ func TestExecDriver_DevicesAndMounts(t *testing.T) {
 	task := &drivers.TaskConfig{
 		ID:         uuid.Generate(),
 		Name:       "test",
+		User:       "root", // need permission to read mounts paths
 		Resources:  testResources,
 		StdoutPath: filepath.Join(tmpDir, "task-stdout"),
 		StderrPath: filepath.Join(tmpDir, "task-stderr"),

drivers/shared/executor/executor_linux.go

@@ -45,26 +45,8 @@ var (
 
 	// ExecutorCgroupMeasuredCpuStats is the list of CPU stats captures by the executor
 	ExecutorCgroupMeasuredCpuStats = []string{"System Mode", "User Mode", "Throttled Periods", "Throttled Time", "Percent"}
-
-	// allCaps is all linux capabilities which is used to configure libcontainer
-	allCaps []string
 )
 
-// initialize the allCaps var with all capabilities available on the system
-func init() {
-	last := capability.CAP_LAST_CAP
-	// workaround for RHEL6 which has no /proc/sys/kernel/cap_last_cap
-	if last == capability.Cap(63) {
-		last = capability.CAP_BLOCK_SUSPEND
-	}
-	for _, cap := range capability.List() {
-		if cap > last {
-			continue
-		}
-		allCaps = append(allCaps, fmt.Sprintf("CAP_%s", strings.ToUpper(cap.String())))
-	}
-}
-
 // LibcontainerExecutor implements an Executor with the runc/libcontainer api
 type LibcontainerExecutor struct {
 	id      string
@@ -569,17 +551,44 @@ func (l *LibcontainerExecutor) handleExecWait(ch chan *waitResult, process *libc
 
 func configureCapabilities(cfg *lconfigs.Config, command *ExecCommand) error {
 	// TODO: allow better control of these
-	cfg.Capabilities = &lconfigs.Capabilities{
-		Bounding:    allCaps,
-		Permitted:   allCaps,
-		Inheritable: allCaps,
-		Ambient:     allCaps,
-		Effective:   allCaps,
+	// use capabilities list as prior to adopting libcontainer in 0.9
+	allCaps := supportedCaps()
+
+	// match capabilities used in Nomad 0.8
+	if command.User == "root" {
+		cfg.Capabilities = &lconfigs.Capabilities{
+			Bounding:    allCaps,
+			Permitted:   allCaps,
+			Effective:   allCaps,
+			Ambient:     nil,
+			Inheritable: nil,
+		}
+	} else {
+		cfg.Capabilities = &lconfigs.Capabilities{
+			Bounding: allCaps,
+		}
 	}
 
 	return nil
 }
 
+// supportedCaps returns a list of all supported capabilities in kernel
+func supportedCaps() []string {
+	allCaps := []string{}
+	last := capability.CAP_LAST_CAP
+	// workaround for RHEL6 which has no /proc/sys/kernel/cap_last_cap
+	if last == capability.Cap(63) {
+		last = capability.CAP_BLOCK_SUSPEND
+	}
+	for _, cap := range capability.List() {
+		if cap > last {
+			continue
+		}
+		allCaps = append(allCaps, fmt.Sprintf("CAP_%s", strings.ToUpper(cap.String())))
+	}
+	return allCaps
+}
+
 // configureIsolation prepares the isolation primitives of the container.
 // The process runs in a container configured with the following:
 //

drivers/shared/executor/executor_linux_test.go

@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strconv"
 	"strings"
 	"testing"
@@ -44,6 +45,7 @@ func testExecutorCommandWithChroot(t *testing.T) *testExecCmd {
 		"/etc/ld.so.cache":  "/etc/ld.so.cache",
 		"/etc/ld.so.conf":   "/etc/ld.so.conf",
 		"/etc/ld.so.conf.d": "/etc/ld.so.conf.d",
+		"/etc/passwd":       "/etc/passwd",
 		"/lib":              "/lib",
 		"/lib64":            "/lib64",
 		"/usr/lib":          "/usr/lib",
@@ -150,7 +152,8 @@ usr/
 /etc/:
 ld.so.cache
 ld.so.conf
-ld.so.conf.d/`
+ld.so.conf.d/
+passwd`
 	tu.WaitForResult(func() (bool, error) {
 		output := testExecCmd.stdout.String()
 		act := strings.TrimSpace(string(output))
@@ -239,6 +242,86 @@ func TestExecutor_EscapeContainer(t *testing.T) {
 	require.NoError(err)
 }
 
+func TestExecutor_Capabilities(t *testing.T) {
+	t.Parallel()
+	testutil.ExecCompatible(t)
+
+	cases := []struct {
+		user string
+		caps string
+	}{
+		{
+			user: "nobody",
+			caps: `
+CapInh: 0000000000000000
+CapPrm: 0000000000000000
+CapEff: 0000000000000000
+CapBnd: 0000003fffffffff
+CapAmb: 0000000000000000`,
+		},
+		{
+			user: "root",
+			caps: `
+CapInh: 0000000000000000
+CapPrm: 0000003fffffffff
+CapEff: 0000003fffffffff
+CapBnd: 0000003fffffffff
+CapAmb: 0000000000000000`,
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.user, func(t *testing.T) {
+			require := require.New(t)
+
+			testExecCmd := testExecutorCommandWithChroot(t)
+			execCmd, allocDir := testExecCmd.command, testExecCmd.allocDir
+			defer allocDir.Destroy()
+
+			execCmd.User = c.user
+			execCmd.ResourceLimits = true
+			execCmd.Cmd = "/bin/bash"
+			execCmd.Args = []string{"-c", "cat /proc/$$/status"}
+
+			executor := NewExecutorWithIsolation(testlog.HCLogger(t))
+			defer executor.Shutdown("SIGKILL", 0)
+
+			_, err := executor.Launch(execCmd)
+			require.NoError(err)
+
+			ch := make(chan interface{})
+			go func() {
+				executor.Wait(context.Background())
+				close(ch)
+			}()
+
+			select {
+			case <-ch:
+				// all good
+			case <-time.After(5 * time.Second):
+				require.Fail("timeout waiting for exec to shutdown")
+			}
+
+			canonical := func(s string) string {
+				s = strings.TrimSpace(s)
+				s = regexp.MustCompile("[ \t]+").ReplaceAllString(s, " ")
+				s = regexp.MustCompile("[\n\r]+").ReplaceAllString(s, "\n")
+				return s
+			}
+
+			expected := canonical(c.caps)
+			tu.WaitForResult(func() (bool, error) {
+				output := canonical(testExecCmd.stdout.String())
+				if !strings.Contains(output, expected) {
+					return false, fmt.Errorf("capabilities didn't match: want\n%v\n; got:\n%v\n", expected, output)
+				}
+				return true, nil
+			}, func(err error) { require.NoError(err) })
+		})
+	}
+
+}
+
 func TestExecutor_ClientCleanup(t *testing.T) {
 	t.Parallel()
 	testutil.ExecCompatible(t)

drivers/shared/executor/executor_test.go

@@ -473,7 +473,7 @@ func setupRootfsBinary(t *testing.T, rootfs, path string) {
 	t.Helper()
 
 	dst := filepath.Join(rootfs, path)
-	err := os.MkdirAll(filepath.Dir(dst), 666)
+	err := os.MkdirAll(filepath.Dir(dst), 0755)
 	require.NoError(t, err)
 
 	src := filepath.Join(