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f5c60ff2da
Linux 3.19 made a change in the handling of setgroups and the 'gid_map' file to address a security issue. The upshot of the 3.19 changes is that in order to update the 'gid_maps' file, use of the setgroups() system call in this user namespace must first be disabled by writing "deny" to one of the /proc/PID/setgroups files for this namespace. Also added tests for remapping uid_map and gid_map inside new user namespace. Fixes #10626 Change-Id: I4d2539acbab741a37092d277e10f31fc39a8feb7 Reviewed-on: https://go-review.googlesource.com/10670 Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
85 lines
2.1 KiB
Go
85 lines
2.1 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build linux
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package syscall_test
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import (
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"os"
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"os/exec"
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"strings"
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"syscall"
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"testing"
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)
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func whoamiCmd(t *testing.T, uid int, setgroups bool) *exec.Cmd {
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if _, err := os.Stat("/proc/self/ns/user"); err != nil {
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if os.IsNotExist(err) {
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t.Skip("kernel doesn't support user namespaces")
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}
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t.Fatalf("Failed to stat /proc/self/ns/user: %v", err)
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}
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cmd := exec.Command("whoami")
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cmd.SysProcAttr = &syscall.SysProcAttr{
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Cloneflags: syscall.CLONE_NEWUSER,
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UidMappings: []syscall.SysProcIDMap{
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{ContainerID: 0, HostID: uid, Size: 1},
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},
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GidMappings: []syscall.SysProcIDMap{
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{ContainerID: 0, HostID: uid, Size: 1},
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},
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GidMappingsEnableSetgroups: setgroups,
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}
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return cmd
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}
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func testNEWUSERRemap(t *testing.T, uid int, setgroups bool) {
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cmd := whoamiCmd(t, uid, setgroups)
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out, err := cmd.CombinedOutput()
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if err != nil {
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t.Fatalf("Cmd failed with err %v, output: %s", err, out)
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}
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sout := strings.TrimSpace(string(out))
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want := "root"
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if sout != want {
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t.Fatalf("whoami = %q; want %q", out, want)
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}
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}
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func TestCloneNEWUSERAndRemapRootDisableSetgroups(t *testing.T) {
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if os.Getuid() != 0 {
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t.Skip("skipping root only test")
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}
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testNEWUSERRemap(t, 0, false)
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}
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func TestCloneNEWUSERAndRemapRootEnableSetgroups(t *testing.T) {
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if os.Getuid() != 0 {
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t.Skip("skipping root only test")
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}
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testNEWUSERRemap(t, 0, false)
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}
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func TestCloneNEWUSERAndRemapNoRootDisableSetgroups(t *testing.T) {
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if os.Getuid() == 0 {
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t.Skip("skipping unprivileged user only test")
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}
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testNEWUSERRemap(t, os.Getuid(), false)
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}
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func TestCloneNEWUSERAndRemapNoRootSetgroupsEnableSetgroups(t *testing.T) {
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if os.Getuid() == 0 {
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t.Skip("skipping unprivileged user only test")
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}
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cmd := whoamiCmd(t, os.Getuid(), true)
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err := cmd.Run()
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if err == nil {
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t.Skip("probably old kernel without security fix")
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}
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if !strings.Contains(err.Error(), "operation not permitted") {
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t.Fatalf("Unprivileged gid_map rewriting with GidMappingsEnableSetgroups must fail")
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}
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}
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