service: token elevation stuff is upstream

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

2 files changed, 14 insertions, 34 deletions

diff --git a/service/service_manager.go b/service/service_manager.go
index dcc8a908..5ffd8615 100644
--- a/service/service_manager.go
+++ b/service/service_manager.go
@@ -111,14 +111,21 @@ func (service *managerService) Execute(args []string, r <-chan svc.ChangeRequest
 			userToken.Close()
 			return
 		}
-		//TODO: The environment that Go gets from CreateEnvironmentBlock seems to have the same PATH as the userToken. Aren't there attacks?
-		elevatedToken, err := getElevatedToken(userToken)
-		if err != nil {
-			log.Printf("Unable to elevate token: %v", err)
-			return
-		}
-		if elevatedToken != userToken {
+		var elevatedToken windows.Token
+		if userToken.IsElevated() {
+			elevatedToken = userToken
+		} else {
+			elevatedToken, err = userToken.GetLinkedToken()
 			userToken.Close()
+			if err != nil {
+				log.Printf("Unable to elevate token: %v", err)
+				return
+			}
+			if !elevatedToken.IsElevated() {
+				elevatedToken.Close()
+				log.Println("Linked token is not elevated")
+				return
+			}
 		}
 		defer elevatedToken.Close()
 		userToken = 0
diff --git a/service/tokens.go b/service/tokens.go
index f203f268..aade8734 100644
--- a/service/tokens.go
+++ b/service/tokens.go
@@ -13,33 +13,6 @@ import (
 	"golang.org/x/sys/windows"
 )
 
-func tokenIsElevated(token windows.Token) bool {
-	var isElevated uint32
-	var outLen uint32
-	err := windows.GetTokenInformation(token, windows.TokenElevation, (*byte)(unsafe.Pointer(&isElevated)), uint32(unsafe.Sizeof(isElevated)), &outLen)
-	if err != nil {
-		return false
-	}
-	return outLen == uint32(unsafe.Sizeof(isElevated)) && isElevated != 0
-}
-
-func getElevatedToken(token windows.Token) (windows.Token, error) {
-	if tokenIsElevated(token) {
-		return token, nil
-	}
-	var linkedToken windows.Token
-	var outLen uint32
-	err := windows.GetTokenInformation(token, windows.TokenLinkedToken, (*byte)(unsafe.Pointer(&linkedToken)), uint32(unsafe.Sizeof(linkedToken)), &outLen)
-	if err != nil {
-		return windows.Token(0), err
-	}
-	if tokenIsElevated(linkedToken) {
-		return linkedToken, nil
-	}
-	linkedToken.Close()
-	return windows.Token(0), errors.New("the linked token is not elevated")
-}
-
 func TokenIsMemberOfBuiltInAdministrator(token windows.Token) bool {
 	adminSid, err := windows.CreateWellKnownSid(windows.WinBuiltinAdministratorsSid)
 	if err != nil {