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// 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 whoamiCmd(t *testing.T, uid, gid int, setgroups bool) *exec.Cmd {
if _, err := os.Stat("/proc/self/ns/user"); err != nil {
if os.IsNotExist(err) {
t.Skip("kernel doesn't support user namespaces")
}
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")
}
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)
}
}
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