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cmd/tailscaled, util/winutil: changes to process and token APIs in winutil

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This PR changes the internal getTokenInfo function to use generics.
I also removed our own implementations for obtaining a token's user
and primary group in favour of calling the ones now available in
x/sys/windows.

Furthermore, I added two new functions for working with tokens, logon
session IDs, and Terminal Services / RDP session IDs.

I modified our privilege enabling code to allow enabling of multiple
privileges via one single function call.

Finally, I added the ProcessImageName function and updated the code in
tailscaled_windows.go to use that instead of directly calling the
underlying API.

All of these changes will be utilized by subsequent PRs pertaining to
this issue.

Updates https://github.com/tailscale/corp/issues/13998

Signed-off-by: Aaron Klotz <aaron@tailscale.com>
pull/10260/head
Aaron Klotz 1 year ago
parent 03e780e9af
commit 855f79fad7
2 changed files with 103 additions and 42 deletions
Show Stats Download Patch File Download Diff File

9
cmd/tailscaled/tailscaled_windows.go
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@ -529,12 +529,11 @@ func uninstallWinTun(logf logger.Logf) {
func fullyQualifiedWintunPath(logf logger.Logf) string {
var dir string
var buf [windows.MAX_PATH]uint16
length := uint32(len(buf))
if err := windows.QueryFullProcessImageName(windows.CurrentProcess(), 0, &buf[0], &length); err != nil {
logf("QueryFullProcessImageName failed: %v", err)
imgName, err := winutil.ProcessImageName(windows.CurrentProcess())
if err != nil {
logf("ProcessImageName failed: %v", err)
} else {
dir = filepath.Dir(windows.UTF16ToString(buf[:length]))
dir = filepath.Dir(imgName)
}
return filepath.Join(dir, "wintun.dll")

134
util/winutil/winutil_windows.go
Unescape Escape View File

@ -225,21 +225,40 @@ func isSIDValidPrincipal(uid string) bool {
}
}
// EnableCurrentThreadPrivilege enables the named privilege in the current
// thread access token. The current goroutine is also locked to the OS thread
// (runtime.LockOSThread). Callers must call the returned disable function when
// done with the privileged task.
func EnableCurrentThreadPrivilege(name string) (disable func() error, err error) {
// EnableCurrentThreadPrivilege enables the named privilege
// in the current thread's access token. The current goroutine is also locked to
// the OS thread (runtime.LockOSThread). Callers must call the returned disable
// function when done with the privileged task.
func EnableCurrentThreadPrivilege(name string) (disable func(), err error) {
return EnableCurrentThreadPrivileges([]string{name})
}
// EnableCurrentThreadPrivileges enables the named privileges
// in the current thread's access token. The current goroutine is also locked to
// the OS thread (runtime.LockOSThread). Callers must call the returned disable
// function when done with the privileged task.
func EnableCurrentThreadPrivileges(names []string) (disable func(), err error) {
runtime.LockOSThread()
if len(names) == 0 {
// Nothing to enable; no-op isn't really an error...
return runtime.UnlockOSThread, nil
}
if err := windows.ImpersonateSelf(windows.SecurityImpersonation); err != nil {
runtime.UnlockOSThread()
return nil, err
}
disable = func() error {
disable = func() {
defer runtime.UnlockOSThread()
return windows.RevertToSelf()
// If RevertToSelf fails, it's not really recoverable and we should panic.
// Failure to do so would leak the privileges we're enabling, which is a
// security issue.
if err := windows.RevertToSelf(); err != nil {
panic(fmt.Sprintf("RevertToSelf failed: %v", err))
}
}
defer func() {
if err != nil {
disable()
@ -254,19 +273,38 @@ func EnableCurrentThreadPrivilege(name string) (disable func() error, err error)
}
defer t.Close()
var tp windows.Tokenprivileges
privStr, err := syscall.UTF16PtrFromString(name)
tp := newTokenPrivileges(len(names))
privs := tp.AllPrivileges()
for i := range privs {
var privStr *uint16
privStr, err = windows.UTF16PtrFromString(names[i])
if err != nil {
return nil, err
}
err = windows.LookupPrivilegeValue(nil, privStr, &tp.Privileges[0].Luid)
err = windows.LookupPrivilegeValue(nil, privStr, &privs[i].Luid)
if err != nil {
return nil, err
}
privs[i].Attributes = windows.SE_PRIVILEGE_ENABLED
}
err = windows.AdjustTokenPrivileges(t, false, tp, 0, nil, nil)
if err != nil {
return nil, err
}
tp.PrivilegeCount = 1
tp.Privileges[0].Attributes = windows.SE_PRIVILEGE_ENABLED
return disable, windows.AdjustTokenPrivileges(t, false, &tp, 0, nil, nil)
return disable, nil
}
func newTokenPrivileges(numPrivs int) *windows.Tokenprivileges {
if numPrivs <= 0 {
panic("numPrivs must be > 0")
}
numBytes := unsafe.Sizeof(windows.Tokenprivileges{}) + (uintptr(numPrivs-1) * unsafe.Sizeof(windows.LUIDAndAttributes{}))
buf := make([]byte, numBytes)
result := (*windows.Tokenprivileges)(unsafe.Pointer(unsafe.SliceData(buf)))
result.PrivilegeCount = uint32(numPrivs)
return result
}
// StartProcessAsChild starts exePath process as a child of parentPID.
@ -346,35 +384,22 @@ func CreateAppMutex(name string) (windows.Handle, error) {
return windows.CreateMutex(nil, false, windows.StringToUTF16Ptr(name))
}
func getTokenInfo(token windows.Token, infoClass uint32) ([]byte, error) {
func getTokenInfo[T any](token windows.Token, infoClass uint32) (*T, error) {
var buf []byte
var desiredLen uint32
err := windows.GetTokenInformation(token, infoClass, nil, 0, &desiredLen)
if err != nil && err != windows.ERROR_INSUFFICIENT_BUFFER {
return nil, err
}
buf := make([]byte, desiredLen)
actualLen := desiredLen
err = windows.GetTokenInformation(token, infoClass, &buf[0], desiredLen, &actualLen)
return buf, err
}
err := windows.GetTokenInformation(token, infoClass, nil, 0, &desiredLen)
func getTokenUserInfo(token windows.Token) (*windows.Tokenuser, error) {
buf, err := getTokenInfo(token, windows.TokenUser)
if err != nil {
return nil, err
for err == windows.ERROR_INSUFFICIENT_BUFFER {
buf = make([]byte, desiredLen)
err = windows.GetTokenInformation(token, infoClass, unsafe.SliceData(buf), desiredLen, &desiredLen)
}
return (*windows.Tokenuser)(unsafe.Pointer(&buf[0])), nil
}
func getTokenPrimaryGroupInfo(token windows.Token) (*windows.Tokenprimarygroup, error) {
buf, err := getTokenInfo(token, windows.TokenPrimaryGroup)
if err != nil {
return nil, err
}
return (*windows.Tokenprimarygroup)(unsafe.Pointer(&buf[0])), nil
return (*T)(unsafe.Pointer(unsafe.SliceData(buf))), nil
}
type tokenElevationType int32
@ -417,12 +442,12 @@ func GetCurrentUserSIDs() (*UserSIDs, error) {
}
defer token.Close()
userInfo, err := getTokenUserInfo(token)
userInfo, err := token.GetTokenUser()
if err != nil {
return nil, err
}
primaryGroup, err := getTokenPrimaryGroupInfo(token)
primaryGroup, err := token.GetTokenPrimaryGroup()
if err != nil {
return nil, err
}
@ -645,3 +670,40 @@ func registerForRestart(opts RegisterForRestartOpts) error {
return nil
}
// ProcessImageName returns the fully-qualified path to the executable image
// associated with process.
func ProcessImageName(process windows.Handle) (string, error) {
var pathBuf [windows.MAX_PATH]uint16
pathBufLen := uint32(len(pathBuf))
if err := windows.QueryFullProcessImageName(process, 0, &pathBuf[0], &pathBufLen); err != nil {
return "", err
}
return windows.UTF16ToString(pathBuf[:pathBufLen]), nil
}
// TSSessionIDToLogonSessionID retrieves the logon session ID associated with
// tsSessionId, which is a Terminal Services / RDP session ID. The calling
// process must be running as LocalSystem.
func TSSessionIDToLogonSessionID(tsSessionID uint32) (logonSessionID windows.LUID, err error) {
var token windows.Token
if err := windows.WTSQueryUserToken(tsSessionID, &token); err != nil {
return logonSessionID, fmt.Errorf("WTSQueryUserToken: %w", err)
}
defer token.Close()
return LogonSessionID(token)
}
type tokenOrigin struct {
originatingLogonSession windows.LUID
}
// LogonSessionID obtains the logon session ID associated with token.
func LogonSessionID(token windows.Token) (logonSessionID windows.LUID, err error) {
origin, err := getTokenInfo[tokenOrigin](token, windows.TokenOrigin)
if err != nil {
return logonSessionID, err
}
return origin.originatingLogonSession, nil
}

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