Linux/macOS: Simplify sudo session detection logic and extend it to macOS

This update simplifies the logic for detecting active sudo sessions by checking the exit code of the sudo -n -l command, which reliably returns 0 if a session is active.

Additionally, this approach is now applicable to recent macOS versions, as they no longer have the sudo bug that previously prevented us from using this method.

src/Core/CoreBase.h

@@ -77,10 +77,8 @@ namespace VeraCrypt
 		virtual void SetFileOwner (const FilesystemPath &path, const UserId &owner) const = 0;
 		virtual DirectoryPath SlotNumberToMountPoint (VolumeSlotNumber slotNumber) const = 0;
 		virtual void WipePasswordCache () const = 0;
-#if defined(TC_LINUX ) || defined (TC_FREEBSD)
 		virtual void ForceUseDummySudoPassword (bool useDummySudoPassword) { UseDummySudoPassword = useDummySudoPassword;}
 		virtual bool GetUseDummySudoPassword () const { return UseDummySudoPassword;}
-#endif
 
 		Event VolumeDismountedEvent;
 		Event VolumeMountedEvent;
@@ -91,9 +89,7 @@ namespace VeraCrypt
 
 		bool DeviceChangeInProgress;
 		FilePath ApplicationExecutablePath;
-#if defined(TC_LINUX ) || defined (TC_FREEBSD)
 		bool UseDummySudoPassword;
-#endif
 
 	private:
 		CoreBase (const CoreBase &);

src/Core/Unix/CoreService.cpp

@@ -292,41 +292,33 @@ namespace VeraCrypt
 			while (!ElevatedServiceAvailable)
 			{
 				//	Test if the user has an active "sudo" session.
-				//	This is only done under Linux / FreeBSD by executing the command 'sudo -n uptime'.
-				//	In case a "sudo" session is active, the result of the command contains the string 'load average'.
-				//	Otherwise, the result contains "sudo: a password is required".
-				//	This may not work on all OSX versions because of a bug in sudo in its version 1.7.10,
-				//	therefore we keep the old behaviour of sending a 'dummy' password under OSX.
-				//	See : https://superuser.com/questions/902826/why-does-sudo-n-on-mac-os-x-always-return-0
-				//
-				//	If for some reason we are getting empty output from pipe, we revert to old behavior
-				//	We also use the old way if the user is forcing the use of dummy password for sudo
-				
-#if defined(TC_LINUX ) || defined (TC_FREEBSD)
 				bool authCheckDone = false;
 				if (!Core->GetUseDummySudoPassword ())
-				{
-					std::vector<char> buffer(128, 0);
-					std::string result;
-					
-					FILE* pipe = popen("sudo -n uptime 2>&1 | grep 'load average' | wc -l | tr -d '[:blank:]'", "r");	//	We redirect stderr to stdout (2>&1) to be able to catch the result of the command
+				{	
+					// sudo man page: "If the -l option was specified without a command, sudo, will exit 
+					//                 with a value of 0 if the user is allowed to run sudo, and they authenticated successfully"
+					// We are using -n to avoid prompting the user for a password.
+					// We are redirecting stderr to stdout and discarding both to avoid any output.
+					// This approach also works on newer macOS versions (12.0 and later).
+					FILE* pipe = popen("sudo -n -l > /dev/null 2>&1", "r");	// redirect stderr to stdout and discard both.
 					if (pipe)
 					{
-						while (!feof(pipe))
-						{
-							if (fgets(buffer.data(), 128, pipe) != nullptr)
-								result += buffer.data();
-						}
-						
-						fflush(pipe);
-						pclose(pipe);
+						// We only care about the exit code  
+						char buf[128];  
+						while (!feof(pipe))  
+						{  
+							if (fgets(buf, sizeof(buf), pipe) == NULL)  
+								break;  
+						}  
+						int status = pclose(pipe);  
 						pipe = NULL;
 						
-						if (!result.empty() && strlen(result.c_str()) != 0)
-						{
-							authCheckDone = true;
-							if (result[0] == '0') // no line found with "load average" text, rerquest admin password
-								(*AdminPasswordCallback) (request.AdminPassword);
+						authCheckDone = true;  
+  
+						// If exit code != 0, user does NOT have an active session => request password  
+						if (status != 0)  
+						{  
+							(*AdminPasswordCallback)(request.AdminPassword);  
 						}
 					}
 					
@@ -336,7 +328,7 @@ namespace VeraCrypt
 						request.FastElevation = false;
 					}
 				}
-#endif				
+			
 				try
 				{
 					request.Serialize (ServiceInputStream);
@@ -353,9 +345,8 @@ namespace VeraCrypt
 					}
 
 					request.FastElevation = false;
-#if defined(TC_LINUX ) || defined (TC_FREEBSD)
+
 					if(!authCheckDone)
-#endif
 						(*AdminPasswordCallback) (request.AdminPassword);
 				}
 			}

src/Main/CommandLineInterface.cpp

@@ -32,9 +32,7 @@ namespace VeraCrypt
 		ArgAllowScreencapture (false),
 		ArgDisableFileSizeCheck (false),
 		ArgUseLegacyPassword (false),
-#if defined(TC_LINUX ) || defined (TC_FREEBSD)
 		ArgUseDummySudoPassword (false),
-#endif
 		StartBackgroundTask (false)
 	{
 		wxCmdLineParser parser;
@@ -376,9 +374,7 @@ namespace VeraCrypt
 
 		ArgDisableFileSizeCheck = parser.Found (L"no-size-check");
 		ArgUseLegacyPassword = parser.Found (L"legacy-password-maxlength");		
-#if defined(TC_LINUX ) || defined (TC_FREEBSD)
 		ArgUseDummySudoPassword = parser.Found (L"use-dummy-sudo-password");
-#endif
 
 #if !defined(TC_WINDOWS) && !defined(TC_MACOSX)
 		if (parser.Found (L"fs-options", &str))

src/Main/CommandLineInterface.h

@@ -87,9 +87,7 @@ namespace VeraCrypt
         bool ArgAllowScreencapture;
         bool ArgDisableFileSizeCheck;
         bool ArgUseLegacyPassword;
-#if defined(TC_LINUX ) || defined (TC_FREEBSD)
         bool ArgUseDummySudoPassword;
-#endif
 
 		bool StartBackgroundTask;
 		UserPreferences Preferences;

src/Main/UserInterface.cpp

@@ -570,9 +570,7 @@ namespace VeraCrypt
 			Core->SetAdminPasswordCallback (shared_ptr <GetStringFunctor> (new AdminPasswordRequestHandler));
 		}
 
-#if defined(TC_LINUX ) || defined (TC_FREEBSD)
 		Core->ForceUseDummySudoPassword (CmdLine->ArgUseDummySudoPassword);
-#endif
 
 		Core->WarningEvent.Connect (EventConnector <UserInterface> (this, &UserInterface::OnWarning));
 		Core->VolumeMountedEvent.Connect (EventConnector <UserInterface> (this, &UserInterface::OnVolumeMounted));