How to use NSTask as root?

In an application I'm making I need to run the following command as root (user will be prompted trice if they really want to, and they will be asked to unmount their drives) using NSTask:

/bin/rm -rf /
#Yes, really

The problem is that simply using Substitute User Do (sudo) doesn't work as the user needs to enter the password to the non-available stdin. I'd rather like to show the user the same window as you'd see when you click the lock in Preferences.app, like this (hopefully with a shorter password):

_{(source: quickpwn.com)}

Can anyone help me with this? Thanks.

Check out STPrivilegedTask, an Objective-C wrapper class around AuthorizationExecuteWithPrivileges() with an NSTask-like interface.

That's one of the hardest tasks to do properly on Mac OS X.

The guide documenting how to do this is the Authorization Services Programming Guide. There are multiple possibilities, as usual the most secure is the hardest to implement.

I've started writing a tool that uses a launchd daemon (the most secure way), the code is available on google code. So if you want, you can copy that code.

I think I can now answer this, thanks to some Googling and a nice find in this SO question. It's very slightly hacky, but IMHO is a satisfactory solution.

I wrote this generic implementation which should achieve what you want:

- (BOOL) runProcessAsAdministrator:(NSString*)scriptPath
                     withArguments:(NSArray *)arguments
                            output:(NSString **)output
                  errorDescription:(NSString **)errorDescription {

    NSString * allArgs = [arguments componentsJoinedByString:@" "];
    NSString * fullScript = [NSString stringWithFormat:@"%@ %@", scriptPath, allArgs];

    NSDictionary *errorInfo = [NSDictionary new];
    NSString *script =  [NSString stringWithFormat:@"do shell script \"%@\" with administrator privileges", fullScript];

    NSAppleScript *appleScript = [[NSAppleScript new] initWithSource:script];
    NSAppleEventDescriptor * eventResult = [appleScript executeAndReturnError:&errorInfo];

    // Check errorInfo
    if (! eventResult)
    {
        // Describe common errors
        *errorDescription = nil;
        if ([errorInfo valueForKey:NSAppleScriptErrorNumber])
        {
            NSNumber * errorNumber = (NSNumber *)[errorInfo valueForKey:NSAppleScriptErrorNumber];
            if ([errorNumber intValue] == -128)
                *errorDescription = @"The administrator password is required to do this.";
        }

        // Set error message from provided message
        if (*errorDescription == nil)
        {
            if ([errorInfo valueForKey:NSAppleScriptErrorMessage])
                *errorDescription =  (NSString *)[errorInfo valueForKey:NSAppleScriptErrorMessage];
        }

        return NO;
    }
    else
    {
        // Set output to the AppleScript's output
        *output = [eventResult stringValue];

        return YES;
    }
}

Usage example:

    NSString * output = nil;
    NSString * processErrorDescription = nil;
    BOOL success = [self runProcessAsAdministrator:@"/usr/bin/id"
                    withArguments:[NSArray arrayWithObjects:@"-un", nil]
                           output:&output
                            errorDescription:&processErrorDescription
                  asAdministrator:YES];


    if (!success) // Process failed to run
    {
         // ...look at errorDescription 
    }
    else
    {
         // ...process output
    }