src/syscall/exec_linux_test.go - go - Git at Google

 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // +build linux

 package syscall_test

 import (
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"strings"
 	"syscall"
 	"testing"
 )

 // Check if we are in a chroot by checking if the inode of / is
 // different from 2 (there is no better test available to non-root on
 // linux).
 func isChrooted(t *testing.T) bool {
 	root, err := os.Stat("/")
 	if err != nil {
 		t.Fatalf("cannot stat /: %v", err)
 	}
 	return root.Sys().(*syscall.Stat_t).Ino != 2
 }

 func checkUserNS(t *testing.T) {
 	if _, err := os.Stat("/proc/self/ns/user"); err != nil {
 		if os.IsNotExist(err) {
 			t.Skip("kernel doesn't support user namespaces")
 		}
 		if os.IsPermission(err) {
 			t.Skip("unable to test user namespaces due to permissions")
 		}
 		t.Fatalf("Failed to stat /proc/self/ns/user: %v", err)
 	}
 	if isChrooted(t) {
 		// create_user_ns in the kernel (see
 		// https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/kernel/user_namespace.c)
 		// forbids the creation of user namespaces when chrooted.
 		t.Skip("cannot create user namespaces when chrooted")
 	}
 	// On some systems, there is a sysctl setting.
 	if os.Getuid() != 0 {
 		data, errRead := ioutil.ReadFile("/proc/sys/kernel/unprivileged_userns_clone")
 		if errRead == nil && data[0] == '0' {
 			t.Skip("kernel prohibits user namespace in unprivileged process")
 		}
 	}
 	// When running under the Go continuous build, skip tests for
 	// now when under Kubernetes. (where things are root but not quite)
 	// Both of these are our own environment variables.
 	// See Issue 12815.
 	if os.Getenv("GO_BUILDER_NAME") != "" && os.Getenv("IN_KUBERNETES") == "1" {
 		t.Skip("skipping test on Kubernetes-based builders; see Issue 12815")
 	}
 }

 func whoamiCmd(t *testing.T, uid, gid int, setgroups bool) *exec.Cmd {
 	checkUserNS(t)
 	cmd := exec.Command("whoami")
 	cmd.SysProcAttr = &syscall.SysProcAttr{
 		Cloneflags: syscall.CLONE_NEWUSER,
 		UidMappings: []syscall.SysProcIDMap{
 			{ContainerID: 0, HostID: uid, Size: 1},
 		},
 		GidMappings: []syscall.SysProcIDMap{
 			{ContainerID: 0, HostID: gid, Size: 1},
 		},
 		GidMappingsEnableSetgroups: setgroups,
 	}
 	return cmd
 }

 func testNEWUSERRemap(t *testing.T, uid, gid int, setgroups bool) {
 	cmd := whoamiCmd(t, uid, gid, setgroups)
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		t.Fatalf("Cmd failed with err %v, output: %s", err, out)
 	}
 	sout := strings.TrimSpace(string(out))
 	want := "root"
 	if sout != want {
 		t.Fatalf("whoami = %q; want %q", out, want)
 	}
 }

 func TestCloneNEWUSERAndRemapRootDisableSetgroups(t *testing.T) {
 	if os.Getuid() != 0 {
 		t.Skip("skipping root only test")
 	}
 	testNEWUSERRemap(t, 0, 0, false)
 }

 func TestCloneNEWUSERAndRemapRootEnableSetgroups(t *testing.T) {
 	if os.Getuid() != 0 {
 		t.Skip("skipping root only test")
 	}
 	testNEWUSERRemap(t, 0, 0, false)
 }

 func TestCloneNEWUSERAndRemapNoRootDisableSetgroups(t *testing.T) {
 	if os.Getuid() == 0 {
 		t.Skip("skipping unprivileged user only test")
 	}
 	testNEWUSERRemap(t, os.Getuid(), os.Getgid(), false)
 }

 func TestCloneNEWUSERAndRemapNoRootSetgroupsEnableSetgroups(t *testing.T) {
 	if os.Getuid() == 0 {
 		t.Skip("skipping unprivileged user only test")
 	}
 	cmd := whoamiCmd(t, os.Getuid(), os.Getgid(), true)
 	err := cmd.Run()
 	if err == nil {
 		t.Skip("probably old kernel without security fix")
 	}
 	if !os.IsPermission(err) {
 		t.Fatalf("Unprivileged gid_map rewriting with GidMappingsEnableSetgroups must fail")
 	}
 }

 func TestEmptyCredGroupsDisableSetgroups(t *testing.T) {
 	cmd := whoamiCmd(t, os.Getuid(), os.Getgid(), false)
 	cmd.SysProcAttr.Credential = &syscall.Credential{}
 	if err := cmd.Run(); err != nil {
 		t.Fatal(err)
 	}
 }

 func TestUnshare(t *testing.T) {
 	// Make sure we are running as root so we have permissions to use unshare
 	// and create a network namespace.
 	if os.Getuid() != 0 {
 		t.Skip("kernel prohibits unshare in unprivileged process, unless using user namespace")
 	}

 	// When running under the Go continuous build, skip tests for
 	// now when under Kubernetes. (where things are root but not quite)
 	// Both of these are our own environment variables.
 	// See Issue 12815.
 	if os.Getenv("GO_BUILDER_NAME") != "" && os.Getenv("IN_KUBERNETES") == "1" {
 		t.Skip("skipping test on Kubernetes-based builders; see Issue 12815")
 	}

 	path := "/proc/net/dev"
 	if _, err := os.Stat(path); err != nil {
 		if os.IsNotExist(err) {
 			t.Skip("kernel doesn't support proc filesystem")
 		}
 		if os.IsPermission(err) {
 			t.Skip("unable to test proc filesystem due to permissions")
 		}
 		t.Fatal(err)
 	}
 	if _, err := os.Stat("/proc/self/ns/net"); err != nil {
 		if os.IsNotExist(err) {
 			t.Skip("kernel doesn't support net namespace")
 		}
 		t.Fatal(err)
 	}

 	orig, err := ioutil.ReadFile(path)
 	if err != nil {
 		t.Fatal(err)
 	}
 	origLines := strings.Split(strings.TrimSpace(string(orig)), "\n")

 	cmd := exec.Command("cat", path)
 	cmd.SysProcAttr = &syscall.SysProcAttr{
 		Unshareflags: syscall.CLONE_NEWNET,
 	}
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		t.Fatalf("Cmd failed with err %v, output: %s", err, out)
 	}

 	// Check there is only the local network interface
 	sout := strings.TrimSpace(string(out))
 	if !strings.Contains(sout, "lo:") {
 		t.Fatalf("Expected lo network interface to exist, got %s", sout)
 	}

 	lines := strings.Split(sout, "\n")
 	if len(lines) >= len(origLines) {
 		t.Fatalf("Got %d lines of output, want <%d", len(lines), len(origLines))
 	}
 }

 func TestGroupCleanup(t *testing.T) {
 	if os.Getuid() != 0 {
 		t.Skip("we need root for credential")
 	}
 	cmd := exec.Command("id")
 	cmd.SysProcAttr = &syscall.SysProcAttr{
 		Credential: &syscall.Credential{
 			Uid: 0,
 			Gid: 0,
 		},
 	}
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		t.Fatalf("Cmd failed with err %v, output: %s", err, out)
 	}
 	strOut := strings.TrimSpace(string(out))
 	expected := "uid=0(root) gid=0(root) groups=0(root)"
 	// Just check prefix because some distros reportedly output a
 	// context parameter; see https://golang.org/issue/16224.
 	if !strings.HasPrefix(strOut, expected) {
 		t.Errorf("id command output: %q, expected prefix: %q", strOut, expected)
 	}
 }

 func TestGroupCleanupUserNamespace(t *testing.T) {
 	if os.Getuid() != 0 {
 		t.Skip("we need root for credential")
 	}
 	checkUserNS(t)
 	cmd := exec.Command("id")
 	uid, gid := os.Getuid(), os.Getgid()
 	cmd.SysProcAttr = &syscall.SysProcAttr{
 		Cloneflags: syscall.CLONE_NEWUSER,
 		Credential: &syscall.Credential{
 			Uid: uint32(uid),
 			Gid: uint32(gid),
 		},
 		UidMappings: []syscall.SysProcIDMap{
 			{ContainerID: 0, HostID: uid, Size: 1},
 		},
 		GidMappings: []syscall.SysProcIDMap{
 			{ContainerID: 0, HostID: gid, Size: 1},
 		},
 	}
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		t.Fatalf("Cmd failed with err %v, output: %s", err, out)
 	}
 	strOut := strings.TrimSpace(string(out))

 	// Strings we've seen in the wild.
 	expected := []string{
 		"uid=0(root) gid=0(root) groups=0(root)",
 		"uid=0(root) gid=0(root) groups=0(root),65534(nobody)",
 		"uid=0(root) gid=0(root) groups=0(root),65534(nogroup)",
 		"uid=0(root) gid=0(root) groups=0(root),65534",
 	}
 	for _, e := range expected {
 		if strOut == e {
 			return
 		}
 	}
 	t.Errorf("id command output: %q, expected one of %q", strOut, expected)
 }
	// Copyright 2015 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// +build linux

	package syscall_test

	import (
	"io/ioutil"
	"os"
	"os/exec"
	"strings"
	"syscall"
	"testing"
	)

	// Check if we are in a chroot by checking if the inode of / is
	// different from 2 (there is no better test available to non-root on
	// linux).
	func isChrooted(t *testing.T) bool {
	root, err := os.Stat("/")
	if err != nil {
	t.Fatalf("cannot stat /: %v", err)
	}
	return root.Sys().(*syscall.Stat_t).Ino != 2
	}

	func checkUserNS(t *testing.T) {
	if _, err := os.Stat("/proc/self/ns/user"); err != nil {
	if os.IsNotExist(err) {
	t.Skip("kernel doesn't support user namespaces")
	}
	if os.IsPermission(err) {
	t.Skip("unable to test user namespaces due to permissions")
	}
	t.Fatalf("Failed to stat /proc/self/ns/user: %v", err)
	}
	if isChrooted(t) {
	// create_user_ns in the kernel (see
	// https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/kernel/user_namespace.c)
	// forbids the creation of user namespaces when chrooted.
	t.Skip("cannot create user namespaces when chrooted")
	}
	// On some systems, there is a sysctl setting.
	if os.Getuid() != 0 {
	data, errRead := ioutil.ReadFile("/proc/sys/kernel/unprivileged_userns_clone")
	if errRead == nil && data[0] == '0' {
	t.Skip("kernel prohibits user namespace in unprivileged process")
	}
	}
	// When running under the Go continuous build, skip tests for
	// now when under Kubernetes. (where things are root but not quite)
	// Both of these are our own environment variables.
	// See Issue 12815.
	if os.Getenv("GO_BUILDER_NAME") != "" && os.Getenv("IN_KUBERNETES") == "1" {
	t.Skip("skipping test on Kubernetes-based builders; see Issue 12815")
	}
	}

	func whoamiCmd(t testing.T, uid, gid int, setgroups bool) exec.Cmd {
	checkUserNS(t)
	cmd := exec.Command("whoami")
	cmd.SysProcAttr = &syscall.SysProcAttr{
	Cloneflags: syscall.CLONE_NEWUSER,
	UidMappings: []syscall.SysProcIDMap{
	{ContainerID: 0, HostID: uid, Size: 1},
	},
	GidMappings: []syscall.SysProcIDMap{
	{ContainerID: 0, HostID: gid, Size: 1},
	},
	GidMappingsEnableSetgroups: setgroups,
	}
	return cmd
	}

	func testNEWUSERRemap(t *testing.T, uid, gid int, setgroups bool) {
	cmd := whoamiCmd(t, uid, gid, setgroups)
	out, err := cmd.CombinedOutput()
	if err != nil {
	t.Fatalf("Cmd failed with err %v, output: %s", err, out)
	}
	sout := strings.TrimSpace(string(out))
	want := "root"
	if sout != want {
	t.Fatalf("whoami = %q; want %q", out, want)
	}
	}

	func TestCloneNEWUSERAndRemapRootDisableSetgroups(t *testing.T) {
	if os.Getuid() != 0 {
	t.Skip("skipping root only test")
	}
	testNEWUSERRemap(t, 0, 0, false)
	}

	func TestCloneNEWUSERAndRemapRootEnableSetgroups(t *testing.T) {
	if os.Getuid() != 0 {
	t.Skip("skipping root only test")
	}
	testNEWUSERRemap(t, 0, 0, false)
	}

	func TestCloneNEWUSERAndRemapNoRootDisableSetgroups(t *testing.T) {
	if os.Getuid() == 0 {
	t.Skip("skipping unprivileged user only test")
	}
	testNEWUSERRemap(t, os.Getuid(), os.Getgid(), false)
	}

	func TestCloneNEWUSERAndRemapNoRootSetgroupsEnableSetgroups(t *testing.T) {
	if os.Getuid() == 0 {
	t.Skip("skipping unprivileged user only test")
	}
	cmd := whoamiCmd(t, os.Getuid(), os.Getgid(), true)
	err := cmd.Run()
	if err == nil {
	t.Skip("probably old kernel without security fix")
	}
	if !os.IsPermission(err) {
	t.Fatalf("Unprivileged gid_map rewriting with GidMappingsEnableSetgroups must fail")
	}
	}

	func TestEmptyCredGroupsDisableSetgroups(t *testing.T) {
	cmd := whoamiCmd(t, os.Getuid(), os.Getgid(), false)
	cmd.SysProcAttr.Credential = &syscall.Credential{}
	if err := cmd.Run(); err != nil {
	t.Fatal(err)
	}
	}

	func TestUnshare(t *testing.T) {
	// Make sure we are running as root so we have permissions to use unshare
	// and create a network namespace.
	if os.Getuid() != 0 {
	t.Skip("kernel prohibits unshare in unprivileged process, unless using user namespace")
	}

	// When running under the Go continuous build, skip tests for
	// now when under Kubernetes. (where things are root but not quite)
	// Both of these are our own environment variables.
	// See Issue 12815.
	if os.Getenv("GO_BUILDER_NAME") != "" && os.Getenv("IN_KUBERNETES") == "1" {
	t.Skip("skipping test on Kubernetes-based builders; see Issue 12815")
	}

	path := "/proc/net/dev"
	if _, err := os.Stat(path); err != nil {
	if os.IsNotExist(err) {
	t.Skip("kernel doesn't support proc filesystem")
	}
	if os.IsPermission(err) {
	t.Skip("unable to test proc filesystem due to permissions")
	}
	t.Fatal(err)
	}
	if _, err := os.Stat("/proc/self/ns/net"); err != nil {
	if os.IsNotExist(err) {
	t.Skip("kernel doesn't support net namespace")
	}
	t.Fatal(err)
	}

	orig, err := ioutil.ReadFile(path)
	if err != nil {
	t.Fatal(err)
	}
	origLines := strings.Split(strings.TrimSpace(string(orig)), "\n")

	cmd := exec.Command("cat", path)
	cmd.SysProcAttr = &syscall.SysProcAttr{
	Unshareflags: syscall.CLONE_NEWNET,
	}
	out, err := cmd.CombinedOutput()
	if err != nil {
	t.Fatalf("Cmd failed with err %v, output: %s", err, out)
	}

	// Check there is only the local network interface
	sout := strings.TrimSpace(string(out))
	if !strings.Contains(sout, "lo:") {
	t.Fatalf("Expected lo network interface to exist, got %s", sout)
	}

	lines := strings.Split(sout, "\n")
	if len(lines) >= len(origLines) {
	t.Fatalf("Got %d lines of output, want <%d", len(lines), len(origLines))
	}
	}

	func TestGroupCleanup(t *testing.T) {
	if os.Getuid() != 0 {
	t.Skip("we need root for credential")
	}
	cmd := exec.Command("id")
	cmd.SysProcAttr = &syscall.SysProcAttr{
	Credential: &syscall.Credential{
	Uid: 0,
	Gid: 0,
	},
	}
	out, err := cmd.CombinedOutput()
	if err != nil {
	t.Fatalf("Cmd failed with err %v, output: %s", err, out)
	}
	strOut := strings.TrimSpace(string(out))
	expected := "uid=0(root) gid=0(root) groups=0(root)"
	// Just check prefix because some distros reportedly output a
	// context parameter; see https://golang.org/issue/16224.
	if !strings.HasPrefix(strOut, expected) {
	t.Errorf("id command output: %q, expected prefix: %q", strOut, expected)
	}
	}

	func TestGroupCleanupUserNamespace(t *testing.T) {
	if os.Getuid() != 0 {
	t.Skip("we need root for credential")
	}
	checkUserNS(t)
	cmd := exec.Command("id")
	uid, gid := os.Getuid(), os.Getgid()
	cmd.SysProcAttr = &syscall.SysProcAttr{
	Cloneflags: syscall.CLONE_NEWUSER,
	Credential: &syscall.Credential{
	Uid: uint32(uid),
	Gid: uint32(gid),
	},
	UidMappings: []syscall.SysProcIDMap{
	{ContainerID: 0, HostID: uid, Size: 1},
	},
	GidMappings: []syscall.SysProcIDMap{
	{ContainerID: 0, HostID: gid, Size: 1},
	},
	}
	out, err := cmd.CombinedOutput()
	if err != nil {
	t.Fatalf("Cmd failed with err %v, output: %s", err, out)
	}
	strOut := strings.TrimSpace(string(out))

	// Strings we've seen in the wild.
	expected := []string{
	"uid=0(root) gid=0(root) groups=0(root)",
	"uid=0(root) gid=0(root) groups=0(root),65534(nobody)",
	"uid=0(root) gid=0(root) groups=0(root),65534(nogroup)",
	"uid=0(root) gid=0(root) groups=0(root),65534",
	}
	for _, e := range expected {
	if strOut == e {
	return
	}
	}
	t.Errorf("id command output: %q, expected one of %q", strOut, expected)
	}