Fix "PR c++/92804 ICE trying to use concept as a nested-name-specifier"

[official-gcc.git] / libgo / go / syscall / exec_linux_test.go

// 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 (
        "flag"
        "fmt"
        "internal/testenv"
        "io"
        "io/ioutil"
        "os"
        "os/exec"
        "os/user"
        "path/filepath"
        "runtime"
        "strconv"
        "strings"
        "syscall"
        "testing"
        "unsafe"
)

func isDocker() bool {
        _, err := os.Stat("/.dockerenv")
        return err == nil
}

func isLXC() bool {
        return os.Getenv("container") == "lxc"
}

func skipInContainer(t *testing.T) {
        // TODO: the callers of this func are using this func to skip
        // tests when running as some sort of "fake root" that's uid 0
        // but lacks certain Linux capabilities. Most of the Go builds
        // run in privileged containers, though, where root is much
        // closer (if not identical) to the real root. We should test
        // for what we need exactly (which capabilities are active?),
        // instead of just assuming "docker == bad". Then we'd get more test
        // coverage on a bunch of builders too.
        if isDocker() {
                t.Skip("skip this test in Docker container")
        }
        if isLXC() {
                t.Skip("skip this test in LXC container")
        }
}

func skipNoUserNamespaces(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)
        }
}

func skipUnprivilegedUserClone(t *testing.T) {
        // Skip the test if the sysctl that prevents unprivileged user
        // from creating user namespaces is enabled.
        data, errRead := ioutil.ReadFile("/proc/sys/kernel/unprivileged_userns_clone")
        if errRead != nil || len(data) < 1 || data[0] == '0' {
                t.Skip("kernel prohibits user namespace in unprivileged process")
        }
}

// 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) {
        skipInContainer(t)
        skipNoUserNamespaces(t)
        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 {
                skipUnprivilegedUserClone(t)
        }
        // On Centos 7 make sure they set the kernel parameter user_namespace=1
        // See issue 16283 and 20796.
        if _, err := os.Stat("/sys/module/user_namespace/parameters/enable"); err == nil {
                buf, _ := ioutil.ReadFile("/sys/module/user_namespace/parameters/enabled")
                if !strings.HasPrefix(string(buf), "Y") {
                        t.Skip("kernel doesn't support user namespaces")
                }
        }

        // On Centos 7.5+, user namespaces are disabled if user.max_user_namespaces = 0
        if _, err := os.Stat("/proc/sys/user/max_user_namespaces"); err == nil {
                buf, errRead := ioutil.ReadFile("/proc/sys/user/max_user_namespaces")
                if errRead == nil && buf[0] == '0' {
                        t.Skip("kernel doesn't support user namespaces")
                }
        }

        // 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, true)
}

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 with permission error; got %v", err)
        }
}

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) {
        skipInContainer(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 {
                if strings.Contains(err.Error(), "operation not permitted") {
                        // Issue 17206: despite all the checks above,
                        // this still reportedly fails for some users.
                        // (older kernels?). Just skip.
                        t.Skip("skipping due to permission error")
                }
                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)"
        // Just check prefix because some distros reportedly output a
        // context parameter; see https://golang.org/issue/16224.
        // Alpine does not output groups; see https://golang.org/issue/19938.
        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",
                "uid=0(root) gid=0(root) groups=0(root),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody),65534(nobody)", // Alpine; see https://golang.org/issue/19938
                "uid=0(root) gid=0(root) groups=0(root) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023",                                                                               // CentOS with SELinux context, see https://golang.org/issue/34547
        }
        for _, e := range expected {
                if strOut == e {
                        return
                }
        }
        t.Errorf("id command output: %q, expected one of %q", strOut, expected)
}

// TestUnshareHelperProcess isn't a real test. It's used as a helper process
// for TestUnshareMountNameSpace.
func TestUnshareMountNameSpaceHelper(*testing.T) {
        if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
                return
        }
        defer os.Exit(0)
        if err := syscall.Mount("none", flag.Args()[0], "proc", 0, ""); err != nil {
                fmt.Fprintf(os.Stderr, "unshare: mount %v failed: %v", os.Args, err)
                os.Exit(2)
        }
}

// Test for Issue 38471: unshare fails because systemd has forced / to be shared
func TestUnshareMountNameSpace(t *testing.T) {
        skipInContainer(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")
        }

        d, err := ioutil.TempDir("", "unshare")
        if err != nil {
                t.Fatalf("tempdir: %v", err)
        }

        cmd := exec.Command(os.Args[0], "-test.run=TestUnshareMountNameSpaceHelper", d)
        cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
        cmd.SysProcAttr = &syscall.SysProcAttr{Unshareflags: syscall.CLONE_NEWNS}

        o, err := cmd.CombinedOutput()
        if err != nil {
                if strings.Contains(err.Error(), ": permission denied") {
                        t.Skipf("Skipping test (golang.org/issue/19698); unshare failed due to permissions: %s, %v", o, err)
                }
                t.Fatalf("unshare failed: %s, %v", o, err)
        }

        // How do we tell if the namespace was really unshared? It turns out
        // to be simple: just try to remove the directory. If it's still mounted
        // on the rm will fail with EBUSY. Then we have some cleanup to do:
        // we must unmount it, then try to remove it again.

        if err := os.Remove(d); err != nil {
                t.Errorf("rmdir failed on %v: %v", d, err)
                if err := syscall.Unmount(d, syscall.MNT_FORCE); err != nil {
                        t.Errorf("Can't unmount %v: %v", d, err)
                }
                if err := os.Remove(d); err != nil {
                        t.Errorf("rmdir after unmount failed on %v: %v", d, err)
                }
        }
}

// Test for Issue 20103: unshare fails when chroot is used
func TestUnshareMountNameSpaceChroot(t *testing.T) {
        skipInContainer(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")
        }

        d, err := ioutil.TempDir("", "unshare")
        if err != nil {
                t.Fatalf("tempdir: %v", err)
        }

        // Since we are doing a chroot, we need the binary there,
        // and it must be statically linked.
        x := filepath.Join(d, "syscall.test")
        cmd := exec.Command(testenv.GoToolPath(t), "test", "-c", "-o", x, "syscall")
        cmd.Env = append(os.Environ(), "CGO_ENABLED=0")
        if o, err := cmd.CombinedOutput(); err != nil {
                t.Fatalf("Build of syscall in chroot failed, output %v, err %v", o, err)
        }

        cmd = exec.Command("/syscall.test", "-test.run=TestUnshareMountNameSpaceHelper", "/")
        cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
        cmd.SysProcAttr = &syscall.SysProcAttr{Chroot: d, Unshareflags: syscall.CLONE_NEWNS}

        o, err := cmd.CombinedOutput()
        if err != nil {
                if strings.Contains(err.Error(), ": permission denied") {
                        t.Skipf("Skipping test (golang.org/issue/19698); unshare failed due to permissions: %s, %v", o, err)
                }
                t.Fatalf("unshare failed: %s, %v", o, err)
        }

        // How do we tell if the namespace was really unshared? It turns out
        // to be simple: just try to remove the executable. If it's still mounted
        // on, the rm will fail. Then we have some cleanup to do:
        // we must force unmount it, then try to remove it again.

        if err := os.Remove(x); err != nil {
                t.Errorf("rm failed on %v: %v", x, err)
                if err := syscall.Unmount(d, syscall.MNT_FORCE); err != nil {
                        t.Fatalf("Can't unmount %v: %v", d, err)
                }
                if err := os.Remove(x); err != nil {
                        t.Fatalf("rm failed on %v: %v", x, err)
                }
        }

        if err := os.Remove(d); err != nil {
                t.Errorf("rmdir failed on %v: %v", d, err)
        }
}

func TestUnshareUidGidMappingHelper(*testing.T) {
        if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
                return
        }
        defer os.Exit(0)
        if err := syscall.Chroot(os.TempDir()); err != nil {
                fmt.Fprintln(os.Stderr, err)
                os.Exit(2)
        }
}

// Test for Issue 29789: unshare fails when uid/gid mapping is specified
func TestUnshareUidGidMapping(t *testing.T) {
        if os.Getuid() == 0 {
                t.Skip("test exercises unprivileged user namespace, fails with privileges")
        }
        checkUserNS(t)
        cmd := exec.Command(os.Args[0], "-test.run=TestUnshareUidGidMappingHelper")
        cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
        cmd.SysProcAttr = &syscall.SysProcAttr{
                Unshareflags:               syscall.CLONE_NEWNS | syscall.CLONE_NEWUSER,
                GidMappingsEnableSetgroups: false,
                UidMappings: []syscall.SysProcIDMap{
                        {
                                ContainerID: 0,
                                HostID:      syscall.Getuid(),
                                Size:        1,
                        },
                },
                GidMappings: []syscall.SysProcIDMap{
                        {
                                ContainerID: 0,
                                HostID:      syscall.Getgid(),
                                Size:        1,
                        },
                },
        }
        out, err := cmd.CombinedOutput()
        if err != nil {
                t.Fatalf("Cmd failed with err %v, output: %s", err, out)
        }
}

type capHeader struct {
        version uint32
        pid     int32
}

type capData struct {
        effective   uint32
        permitted   uint32
        inheritable uint32
}

const CAP_SYS_TIME = 25
const CAP_SYSLOG = 34

type caps struct {
        hdr  capHeader
        data [2]capData
}

func getCaps() (caps, error) {
        var c caps

        // Get capability version
        if _, _, errno := syscall.Syscall(syscall.SYS_CAPGET, uintptr(unsafe.Pointer(&c.hdr)), uintptr(unsafe.Pointer(nil)), 0); errno != 0 {
                return c, fmt.Errorf("SYS_CAPGET: %v", errno)
        }

        // Get current capabilities
        if _, _, errno := syscall.Syscall(syscall.SYS_CAPGET, uintptr(unsafe.Pointer(&c.hdr)), uintptr(unsafe.Pointer(&c.data[0])), 0); errno != 0 {
                return c, fmt.Errorf("SYS_CAPGET: %v", errno)
        }

        return c, nil
}

func mustSupportAmbientCaps(t *testing.T) {
        var uname syscall.Utsname
        if err := syscall.Uname(&uname); err != nil {
                t.Fatalf("Uname: %v", err)
        }
        var buf [65]byte
        for i, b := range uname.Release {
                buf[i] = byte(b)
        }
        ver := string(buf[:])
        if i := strings.Index(ver, "\x00"); i != -1 {
                ver = ver[:i]
        }
        if strings.HasPrefix(ver, "2.") ||
                strings.HasPrefix(ver, "3.") ||
                strings.HasPrefix(ver, "4.1.") ||
                strings.HasPrefix(ver, "4.2.") {
                t.Skipf("kernel version %q predates required 4.3; skipping test", ver)
        }
}

// TestAmbientCapsHelper isn't a real test. It's used as a helper process for
// TestAmbientCaps.
func TestAmbientCapsHelper(*testing.T) {
        if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
                return
        }
        defer os.Exit(0)

        caps, err := getCaps()
        if err != nil {
                fmt.Fprintln(os.Stderr, err)
                os.Exit(2)
        }
        if caps.data[0].effective&(1<<uint(CAP_SYS_TIME)) == 0 {
                fmt.Fprintln(os.Stderr, "CAP_SYS_TIME unexpectedly not in the effective capability mask")
                os.Exit(2)
        }
        if caps.data[1].effective&(1<<uint(CAP_SYSLOG&31)) == 0 {
                fmt.Fprintln(os.Stderr, "CAP_SYSLOG unexpectedly not in the effective capability mask")
                os.Exit(2)
        }
}

func TestAmbientCaps(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")
        }

        testAmbientCaps(t, false)
}

func TestAmbientCapsUserns(t *testing.T) {
        checkUserNS(t)
        testAmbientCaps(t, true)
}

func testAmbientCaps(t *testing.T, userns bool) {
        skipInContainer(t)
        mustSupportAmbientCaps(t)

        skipUnprivilegedUserClone(t)

        // skip on android, due to lack of lookup support
        if runtime.GOOS == "android" {
                t.Skip("skipping test on android; see Issue 27327")
        }

        u, err := user.Lookup("nobody")
        if err != nil {
                t.Fatal(err)
        }
        uid, err := strconv.ParseInt(u.Uid, 0, 32)
        if err != nil {
                t.Fatal(err)
        }
        gid, err := strconv.ParseInt(u.Gid, 0, 32)
        if err != nil {
                t.Fatal(err)
        }

        // Copy the test binary to a temporary location which is readable by nobody.
        f, err := ioutil.TempFile("", "gotest")
        if err != nil {
                t.Fatal(err)
        }
        defer os.Remove(f.Name())
        defer f.Close()
        e, err := os.Open(os.Args[0])
        if err != nil {
                t.Fatal(err)
        }
        defer e.Close()
        if _, err := io.Copy(f, e); err != nil {
                t.Fatal(err)
        }
        if err := f.Chmod(0755); err != nil {
                t.Fatal(err)
        }
        if err := f.Close(); err != nil {
                t.Fatal(err)
        }

        cmd := exec.Command(f.Name(), "-test.run=TestAmbientCapsHelper")
        cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
        cmd.Stdout = os.Stdout
        cmd.Stderr = os.Stderr
        cmd.SysProcAttr = &syscall.SysProcAttr{
                Credential: &syscall.Credential{
                        Uid: uint32(uid),
                        Gid: uint32(gid),
                },
                AmbientCaps: []uintptr{CAP_SYS_TIME, CAP_SYSLOG},
        }
        if userns {
                cmd.SysProcAttr.Cloneflags = syscall.CLONE_NEWUSER
                const nobody = 65534
                uid := os.Getuid()
                gid := os.Getgid()
                cmd.SysProcAttr.UidMappings = []syscall.SysProcIDMap{{
                        ContainerID: int(nobody),
                        HostID:      int(uid),
                        Size:        int(1),
                }}
                cmd.SysProcAttr.GidMappings = []syscall.SysProcIDMap{{
                        ContainerID: int(nobody),
                        HostID:      int(gid),
                        Size:        int(1),
                }}

                // Set credentials to run as user and group nobody.
                cmd.SysProcAttr.Credential = &syscall.Credential{
                        Uid: nobody,
                        Gid: nobody,
                }
        }
        if err := cmd.Run(); err != nil {
                t.Fatal(err.Error())
        }
}