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user_chpwd_union_id.go
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user_chpwd_union_id.go
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// SPDX-FileCopyrightText: 2018 - 2022 UnionTech Software Technology Co., Ltd.
//
// SPDX-License-Identifier: GPL-3.0-or-later
package accounts
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"os"
"os/exec"
"os/user"
"path"
"path/filepath"
"strconv"
"strings"
"sync"
"syscall"
"time"
"github.com/godbus/dbus/v5"
"github.com/linuxdeepin/dde-daemon/accounts1/users"
authenticate "github.com/linuxdeepin/go-dbus-factory/system/org.deepin.dde.authenticate1"
login1 "github.com/linuxdeepin/go-dbus-factory/system/org.freedesktop.login1"
"github.com/linuxdeepin/go-lib/dbusutil"
"github.com/linuxdeepin/go-lib/procfs"
)
// 这里出于安全考虑, 一方面为了防止被 debug, 另一方面为了防止环境变量被篡改,
// 所以需要将重置密码的对话框 (文件位于 resetPwdDialogPath)
// 以一个特殊的用户的身份运行, 这个用户只做运行对话框这一件事情.
const pwdChangerUserName = "nobody" //#nosec G101
const resetPwdDialogPath = "/usr/lib/dde-control-center/reset-password-dialog" //#nosec G101
// copy from golang 1.17, comment out some code because of unexported member
//
// String returns a human-readable description of c.
// It is intended only for debugging.
// In particular, it is not suitable for use as input to a shell.
// The output of String may vary across Go releases.
func cmdToString(c *exec.Cmd) string {
// if c.lookPathErr != nil {
// // failed to resolve path; report the original requested path (plus args)
// return strings.Join(c.Args, " ")
// }
// report the exact executable path (plus args)
b := new(strings.Builder)
b.WriteString(c.Path)
for _, a := range c.Args[1:] {
b.WriteByte(' ')
b.WriteString(a)
}
return b.String()
}
// caller 表示启动短信验证码更改密码过程的调用者
type caller struct {
display string
xauth string
app string
wayland string // wayland socket, almost "/run/user/{UID}/wayland-0"
proc procfs.Process
user *user.User // 启动更改密码过程的用户, 不是被改密码的用户
}
// 创建 caller 对象
// 此函数主要负责验证调用者身份 (通过验证其二进制路径), 并获得其 .Xauthority 文件位置, 以及 DISPLAY 变量
// note: 尽量避免从调用者的环境变量中获取数值
func newCaller(service *dbusutil.Service, sender dbus.Sender) (ret *caller, err error) {
pid, err := service.GetConnPID(string(sender))
if err != nil {
err = fmt.Errorf("fail to get sender PID: %v", err)
return
}
proc := procfs.Process(pid)
exe, err := proc.Exe()
if err != nil {
err = fmt.Errorf("get sender exe error: %v", err)
return
}
// 只允许来自控制中心, 锁屏和 greetter 的调用
var app string
switch exe {
case "/usr/bin/dde-control-center":
app = "control-center"
case "/usr/bin/dde-lock":
app = "lock"
case "/usr/bin/lightdm-deepin-greeter":
app = "greeter"
default:
err = fmt.Errorf("set password with Union ID called by %s, which is not allow", exe)
return
}
status, err := proc.Status()
if err != nil {
err = fmt.Errorf("failed to get sender status: %v", err)
return
}
uids, err := status.Uids()
if err != nil {
err = fmt.Errorf("failed to get sender euid: %v", err)
return
}
uid := uids[1] // EUID
user, err := user.LookupId(fmt.Sprint(uid))
if err != nil {
err = fmt.Errorf("failed to lookup sender username: %v", err)
return
}
envs, err := proc.Environ()
if err != nil {
err = fmt.Errorf("failed to get sender environment variables: %v", err)
return
}
login1Manager := login1.NewManager(service.Conn())
userObjectPath, err := login1Manager.GetUserByPID(0, pid)
if err != nil {
err = fmt.Errorf("fail to get sender user path: %v", err)
return
}
userDbus, err := login1.NewUser(service.Conn(), userObjectPath)
if err != nil {
err = fmt.Errorf("new user failed: %v", err)
return
}
sessionInfo, err := userDbus.Display().Get(0)
if err != nil {
err = fmt.Errorf("fail to get display session info: %v", err)
return
}
session, err := login1.NewSession(service.Conn(), sessionInfo.Path)
if err != nil {
err = fmt.Errorf("fail to create session object proxy: %v", err)
return
}
display, err := session.Display().Get(0)
if err != nil {
err = fmt.Errorf("fail to get sender display: %v", err)
return
}
sessionType, err := session.Type().Get(0)
if err != nil {
err = fmt.Errorf("fail to get sender session type: %v", err)
return
}
waylandSocket := getWaylandSocket(envs)
if sessionType == "wayland" && waylandSocket == "" {
err = fmt.Errorf("failed to get wayland socket")
return
}
xauth, found := envs.Lookup("XAUTHORITY")
if !found {
// $HOME/.Xauthority is default authority file if XAUTHORITY isn't defined.
xauth = filepath.Join(user.HomeDir, ".Xauthority")
}
ret = &caller{
display: display,
xauth: xauth,
proc: proc,
user: user,
app: app,
wayland: waylandSocket,
}
return
}
func getWaylandSocket(envs procfs.EnvVars) (waylandSocket string) {
run, found := envs.Lookup("XDG_RUNTIME_DIR")
if !found {
return ""
}
display, found := envs.Lookup("WAYLAND_DISPLAY")
if !found {
return ""
}
return path.Join(run, display)
}
type pwdChanger interface {
clean() // clean all stuff relay to pwdChanger
runDialog() (*os.Process, error) // run the dialog
wait() // wait dialog close
}
type pwdChangerBase struct {
targetUser *User
selfUid int
selfGid int
cmd *exec.Cmd
stdin io.WriteCloser
stdout io.ReadCloser
stderr io.ReadCloser
readPipe *os.File
writePipe *os.File
}
type pwdChangerX struct {
*pwdChangerBase
xauthDir string
}
type pwdChangerWayland struct {
*pwdChangerBase
waylandSocket string
}
func (pcr *pwdChangerBase) runDialog() (*os.Process, error) {
// start dialog
logger.Debugf("set password with union id: run \"%s\", envs: %v", cmdToString(pcr.cmd), pcr.cmd.Env)
pcr.cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
err := pcr.cmd.Start()
if err != nil {
err = fmt.Errorf("fail to start reset-password-dialog: %v", err)
}
return pcr.cmd.Process, err
}
func (pcr *pwdChangerBase) wait() {
// close writePipe which is the write end fd has been passed to and used by dialog
err := pcr.writePipe.Close()
if err != nil {
logger.Warningf("fail to close write side of pipe: %v", err)
}
rpipeReader := bufio.NewReader(pcr.readPipe)
stdinWriter := bufio.NewWriter(pcr.stdin)
// read shadowed pwd from dialog, this input should end with a '\n'
line, err := rpipeReader.ReadString('\n')
if err != nil {
logger.Warningf("set password with union ID: read line from reset-password-dialog failed: %v", err)
_, _ = stdinWriter.Write([]byte(fmt.Sprintf("fail to read from reset-password-dialog: %v\n", err)))
_ = stdinWriter.Flush()
return
}
// remove '\n'
line = line[:len(line)-1]
// modify password
err = users.ModifyPasswd(line, pcr.targetUser.UserName)
if err != nil {
logger.Warningf("set password with union ID: fail to modify password: %v", err)
_, _ = stdinWriter.Write([]byte(fmt.Sprintf("fail to modify password: %v\n", err)))
_ = stdinWriter.Flush()
return
}
// send success message to dialog
_, err = stdinWriter.Write([]byte("success\n"))
_ = stdinWriter.Flush()
if err != nil {
logger.Warningf("set password with union ID: fail to write success message: %v", err)
}
// reset limits
auth := authenticate.NewAuthenticate(pcr.targetUser.service.Conn())
err = auth.ResetLimits(0, pcr.targetUser.UserName)
if err != nil {
logger.Warningf("set password with union ID: fail to reset limits: %v", err)
}
// force remove user's login keyring, since the data inside is useless
err = removeLoginKeyring(pcr.targetUser)
if err != nil {
logger.Warningf("remove login keyring fail: %v", err)
}
stderrBuf := new(bytes.Buffer)
stdoutBuf := new(bytes.Buffer)
stdoutReader := bufio.NewReader(pcr.stdout)
stderrReader := bufio.NewReader(pcr.stderr)
_, err = io.Copy(stderrBuf, stderrReader)
if err != nil {
logger.Warningf("fail to get stderr of reset-password-dialog: %v", err)
}
_, err = io.Copy(stdoutBuf, stdoutReader)
if err != nil {
logger.Warningf("fail to get stdout of reset-password-dialog: %v", err)
}
err = pcr.cmd.Wait()
if err != nil {
logger.Warningf("reset-password-dialog exited: %v\nstderr:\n%v\nstdout:\n%v", err, stderrBuf, stdoutBuf)
}
// Terminate all sessions of this user, since its password is changed, and keyring has been force removed
login1Manager := login1.NewManager(pcr.targetUser.service.Conn())
uid, err := strconv.Atoi(pcr.targetUser.Uid)
if err != nil {
logger.Warningf("fail to get convert uid==%d: %v", uid, err)
return
}
userPath, err := login1Manager.GetUser(0, uint32(uid))
if err != nil {
logger.Infof("fail to get user by uid==%d: %v", uid, err)
return
}
login1User, err := login1.NewUser(pcr.targetUser.service.Conn(), userPath)
if err != nil {
logger.Warningf("fail to create login1 User Object: %v", err)
return
}
err = login1User.Terminate(0)
if err != nil {
logger.Warningf("fail to terminate user session: %v", err)
return
}
return
}
// clean all stuff relay to pwdChanger
func (pcrb *pwdChangerBase) clean() {
err := pcrb.readPipe.Close()
if err != nil {
logger.Warningf("fail to close read end of pipe: %v", err)
}
}
func (pcrx *pwdChangerX) clean() {
pcrx.pwdChangerBase.clean()
err := os.RemoveAll(pcrx.xauthDir)
if err != nil {
logger.Warningf("fail to remove tmp xauth dir: %v", err)
}
}
func (pcrw *pwdChangerWayland) clean() {
pcrw.pwdChangerBase.clean()
if err := runSetfacl(pwdChangerUserName, pcrw.waylandSocket, false); err != nil {
logger.Warningf("fail to clean acl for wayland socket: %v", err)
}
if err := runSetfacl(pwdChangerUserName, filepath.Dir(pcrw.waylandSocket), false); err != nil {
logger.Warningf("fail to clean acl for wayland socket directory: %v", err)
}
return
}
func newPwdChangerBase(caller *caller, u *User) (ret *pwdChangerBase, err error) {
pwdChangerUser, err := user.Lookup(pwdChangerUserName)
if err != nil {
err = fmt.Errorf("fail to get user info of %s: %v", pwdChangerUserName, err)
return
}
selfUid, err := strconv.Atoi(pwdChangerUser.Uid)
if err != nil {
err = fmt.Errorf("fail to convert uid to int: %v", err)
return
}
selfGid, err := strconv.Atoi(pwdChangerUser.Gid)
if err != nil {
err = fmt.Errorf("fail to convert gid to int: %v", err)
return
}
// 检验可执行文件的属性
fInfo, err := os.Stat(resetPwdDialogPath)
if err != nil {
err = fmt.Errorf("get reset-password-dislog stat fail: %v", err)
return
}
fileSys := fInfo.Sys()
stat, ok := fileSys.(*syscall.Stat_t)
if !ok {
err = errors.New("fail to get stat of reset-password-dialog")
return
}
// TODO does this convert to uint32 safe?
if !(fInfo.Mode() == 0500 && stat.Uid == uint32(selfUid)) {
err = errors.New("reset-password-dialog permission check failed")
return
}
// create pipe for dialog to send shadowed pwd
readPipe, writePipe, err := os.Pipe()
if err != nil {
err = fmt.Errorf("fail to create pipe: %v", err)
return
}
// -u 用户名
// -a 应用类型
// --fd 传递密码使用的文件描述符
cmd := exec.Command(
"runuser", "-u", pwdChangerUser.Username, "--",
resetPwdDialogPath, "-u", u.UserName, "-a", caller.app,
"--fd", "3") //#nosec G204
cmd.ExtraFiles = append(cmd.ExtraFiles, writePipe)
stdin, err := cmd.StdinPipe()
if err != nil {
err = fmt.Errorf("get stdinpipe failed: %v", err)
return
}
stdout, err := cmd.StdoutPipe()
if err != nil {
err = fmt.Errorf("get stdoutpipe failed: %v", err)
return
}
stderr, err := cmd.StderrPipe()
if err != nil {
err = fmt.Errorf("get stderrpipe failed: %v", err)
return
}
cmd.Env = append(
cmd.Env,
"LANG="+u.Locale,
"LANGUAGE="+u.Locale,
)
ret = &pwdChangerBase{
targetUser: u,
selfUid: selfUid,
selfGid: selfGid,
cmd: cmd,
stdin: stdin,
stdout: stdout,
stderr: stderr,
readPipe: readPipe,
writePipe: writePipe,
}
return
}
// 此函数负责初始化用于更改密码的用户
// 对话框的语言和被修改密码的用户的语言设置保持一致
func newPwdChanger(caller *caller, u *User) (ret pwdChanger, err error) {
pcrb, err := newPwdChangerBase(caller, u)
if err != nil {
logger.Warning(err)
return
}
if caller.wayland == "" {
ret, err = newPwdChangerX(caller, u, pcrb)
} else {
ret, err = newPwdChangerWayland(caller, u, pcrb)
}
return
}
// 此函数负责将来自 caller 的 xauth 凭证发送给 deepin_pwd_changer 用户
func newPwdChangerX(caller *caller, u *User, base *pwdChangerBase) (ret *pwdChangerX, err error) {
xAuthDir := filepath.Join("/run", "user", fmt.Sprint(base.selfUid))
defer func() {
if err != nil {
err := os.RemoveAll(xAuthDir)
if err != nil {
logger.Warningf("fail to remove tmp xauth dir: %v", err)
}
}
}()
err = os.Mkdir(xAuthDir, os.FileMode(0700))
if err != nil {
if os.IsExist(err) {
logger.Warningf("path %s existed, remove it now", xAuthDir)
err = os.RemoveAll(xAuthDir)
if err != nil {
err = fmt.Errorf("fail to remove existed dir that hold .Xauthority: %v", err)
return
}
err = os.Mkdir(xAuthDir, os.FileMode(0700))
}
if err != nil {
err = fmt.Errorf("fail to create dir that hold .Xauthority: %v", err)
return
}
}
err = os.Chown(xAuthDir, base.selfUid, base.selfGid)
if err != nil {
err = fmt.Errorf("fail to chown dir that hold .Xauthority: %v", err)
return
}
xauthPath := filepath.Join(xAuthDir, ".Xauthority")
file, err := os.Create(xauthPath)
if err != nil {
err = fmt.Errorf("fail to create .Xauthority: %v", err)
return
}
err = file.Chown(base.selfUid, base.selfGid)
if err != nil {
err = fmt.Errorf("fail to chown .Xauthority: %v", err)
return
}
err = file.Close()
if err != nil {
err = fmt.Errorf("fail to close .Xauthority: %v", err)
return
}
// get caller's xauth
cmd := exec.Command("runuser", "-u", caller.user.Username, "--", "xauth", "list") //#nosec G204
cmd.Env = append(cmd.Env, "XAUTHORITY="+caller.xauth)
logger.Debugf("set password with union id: run \"%s\", envs: %v", cmdToString(cmd), cmd.Env)
xauths, err := cmd.Output()
if err != nil {
err = fmt.Errorf("get xauth cookie failed: %v", err)
return
}
// Add all xauth entries from caller to pwdChanger
// After change hostname, some werid things happen to .Xauthority before a reboot
// The prefix match not working here. So we have to add all entries to pwdChanger's .Xauthority file
lines := strings.Split(string(xauths), "\n")
args := []string{"-u", pwdChangerUserName, "--", "xauth", "add"}
for _, line := range lines {
fields := strings.Split(line, " ")
if fields[0] == "" {
continue
}
arg := append(args, fields...)
cmd = exec.Command("runuser", arg...) //#nosec G204
cmd.Env = append(cmd.Env, "XAUTHORITY="+xauthPath)
logger.Debugf("set password with union id: run \"%s\", envs: %v", cmdToString(cmd), cmd.Env)
err = cmd.Run()
if err != nil {
err = fmt.Errorf("add xauth fail: %v", err)
return
}
}
base.cmd.Env = append(base.cmd.Env,
"XAUTHORITY="+xauthPath,
"DISPLAY="+caller.display,
)
ret = &pwdChangerX{
pwdChangerBase: base,
xauthDir: xAuthDir,
}
return
}
func runSetfacl(user string, filePath string, isEnable bool) (err error) {
flag := "-x" // remove
perms := ""
if isEnable {
flag = "-m" // modify
perms = ":rwx"
}
cmd := exec.Command("setfacl", flag, "u:"+user+perms, filePath) //#nosec G204
logger.Debugf("set password with union id: run \"%s\", envs: %v", cmdToString(cmd), cmd.Env)
err = cmd.Run()
return
}
// 此函数负责临时允许 deepin_pwd_changer 用户访问目标用户的 wayland socket
func newPwdChangerWayland(caller *caller, u *User, base *pwdChangerBase) (ret *pwdChangerWayland, err error) {
if err = runSetfacl(pwdChangerUserName, caller.wayland, true); err != nil {
return
}
if err = runSetfacl(pwdChangerUserName, filepath.Dir(caller.wayland), true); err != nil {
return
}
base.cmd.Env = append(base.cmd.Env,
"XDG_SESSION_TYPE=wayland",
"QT_WAYLAND_SHELL_INTEGRATION=kwayland-shell", // env copy from startdde-wayland
"WAYLAND_DISPLAY="+caller.wayland,
)
ret = &pwdChangerWayland{
pwdChangerBase: base,
waylandSocket: caller.wayland,
}
return
}
func (u *User) setPwdWithUnionID(sender dbus.Sender) (err error) {
// 在应用真实启动前发生的错误, 应该要和 dbus 方法一起返回
// 在应用启动后发生的错误, 会输出在后端的日志中.
// 这里使用一个管道来传递错误信息
return doSetPwdWithUnionID(u, sender, 3)
}
var pwdChangerLock sync.Mutex
var pwdChangerProcess *os.Process
func doSetPwdWithUnionID(u *User, sender dbus.Sender, count int) error {
pwdChangerLock.Lock()
if pwdChangerProcess != nil {
err := syscall.Kill(-pwdChangerProcess.Pid, syscall.SIGTERM)
if err != nil {
logger.Warning(err)
}
pwdChangerLock.Unlock()
// 等待协程结束
if count > 0 {
logger.Debug("retry after 100ms")
time.Sleep(100 * time.Millisecond)
return doSetPwdWithUnionID(u, sender, count-1)
} else {
return fmt.Errorf("kill pwd changer process failed")
}
}
caller, err := newCaller(u.service, sender)
if err != nil {
pwdChangerLock.Unlock()
return fmt.Errorf("newCaller failed: %v", err)
}
pcr, err := newPwdChanger(caller, u)
if err != nil {
pwdChangerLock.Unlock()
return fmt.Errorf("setup pwdChanger fail: %v", err)
}
pwdChangerProcess, err = pcr.runDialog()
pwdChangerLock.Unlock()
if err != nil {
pcr.clean()
return err
}
go func() {
defer func() {
pwdChangerLock.Lock()
pwdChangerProcess = nil
pwdChangerLock.Unlock()
}()
pcr.wait()
pcr.clean()
}()
return nil
}
// 删除用户的 login keyring
// 由于重置密码时没有输入原密码, 所以恢复 keyring 中的数据是不可能的, 只能直接移除掉.
func removeLoginKeyring(user *User) (err error) {
// FIXME
// greeter 界面触发该功能时 user 的 session bus 不存在,
// 所以只能简单地直接删除文件, 而不可能通过 keyring 的 daemon 删除密钥环
// FIXME login keyring 的位置有没可能变化?
err = os.Remove(user.HomeDir + "/.local/share/keyrings/login.keyring")
return
}