Hi all,
Our company has an application that runs on several machines, this app is launched via a deamon that keeps it alive.
One of the feature of this app, is to start a headless electron application to run some tests. When spawning this electron application with the new arm64 OS, we are getting this issue:
Silent Test Agent Worker exited with code: 133
[ERROR] [75873:0205/135842.347044:ERROR:mach_port_rendezvous.cc(384)] bootstrap_look_up com.hivestreaming.silenttestagent.MachPortRendezvousServer.1: Permission denied (1100)
[ERROR] [75873:0205/135842.347417:ERROR:shared_memory_switch.cc(237)] No rendezvous client, terminating process (parent died?)
[ERROR] [75872:0205/135842.347634:ERROR:mach_port_rendezvous.cc(384)] bootstrap_look_up com.hivestreaming.silenttestagent.MachPortRendezvousServer.1: Permission denied (1100)
[ERROR] [75872:0205/135842.347976:ERROR:shared_memory_switch.cc(237)] No rendezvous client, terminating process (parent died?)
Both application (main app and electron one) are signed and notarized, but it seems that there is some other permission issue.
If we run the electron application manually, all runs as expected.
I added the crash report as attachment
CrashReport.log
Processes & Concurrency
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MacOS Version: 14.7.2
macOS SDKs:
macOS 14.5 -sdk macosx14.5
I am working on a sample program for validation Against:
Team Identifier
Developer ID
I started with validating Team Identifier, but my validation is not working and it is allowing to launch programs which are not matching the team identifier in the signature.
Below is my code:
func verifyExecutableWithLCR(executablePath: String, arguments: [String]) -> Bool {
let task = Process()
task.launchPath = executablePath
task.arguments = arguments
if #available(macOS 14.4, *) {
print("launchRequirementData is available on this system.")
do {
let req = try OnDiskCodeRequirement.allOf {
TeamIdentifier("ABCDEFGHI")
//SigningIdentifier("com.***.client.***-Client.****")
}
let encoder = PropertyListEncoder()
encoder.outputFormat = .xml
let requirementData = try encoder.encode(req)
task.launchRequirementData = requirementData
print("launchRequirementData is set.")
try task.run()
print("[SUCCESS] Executable passed the code signature verification.")
return true
} catch {
print("[ERROR] Code signature verification failed: \(error.localizedDescription)")
return false
}
} else {
print("[WARNING] launchRequirement is not available on this macOS version.")
return false
}
}
Could you please help me in identifying whay am I doing wrong here?
We would be creating N NWListener objects and M NWConnection objects in our process' communication subsystem to create server sockets, accepted client sockets on server and client sockets on clients.
Both NWConnection and NWListener rely on DispatchQueue to deliver state changes, incoming connections, send/recv completions etc.
What DispatchQueues should I use and why?
Global Concurrent Dispatch Queue (and which QoS?) for all NWConnection and NWListener
One custom concurrent queue (which QoS?) for all NWConnection and NWListener? (Does that anyways get targetted to one of the global queues?)
One custom concurrent queue per NWConnection and NWListener though all targetted to Global Concurrent Dispatch Queue (and which QoS?)?
One custom concurrent queue per NWConnection and NWListener though all targetted to single target custom concurrent queue?
For every option above, how am I impacted in terms of parallelism, concurrency, throughput & latency and how is overall system impacted (with other processes also running)?
Seperate questions (sorry for the digression):
Are global concurrent queues specific to a process or shared across all processes on a device?
Can I safely use setSpecific on global dispatch queues in our app?
I understand that GCD and it's underlying implementations have evolved over time. And many things have not been shared explicitly in Apple documentation.
The most concepts of DispatchQueue (serial and concurrent queues), DispatchQoS, target queue and system provided queues: main and globals etc.
I have some doubts & questions to clarify:
[Main Dispatch Queue] [Link] Because the main queue doesn't behave entirely like a regular serial queue, it may have unwanted side-effects when used in processes that are not UI apps (daemons). For such processes, the main queue should be avoided. What does it mean? Can you elaborate?
[Global Concurrent Dispatch Queues] Are they global to a process or across processes on a device. I believe it is the first case but just wanted to be sure.
[Global Concurrent Dispatch Queues] Does system create 4 (for each QoS) * 2 (over-commiting and non-overcommiting queues) = 8 queues in all. When does which type of queue comes into play?
[Custom Queue][Target Queue concept] [swift-corelibs-libdispatch/man/dispatch_queue_create.3] QUOTE The default target queue of all dispatch objects created by the application is the default priority global concurrent queue. UNQUOTE Is this stil true?
We could not find a mention of this in any latest official apple documentation (though some old forum threads (one more) and github code documentation indicate the same).
The official documentation only says:
[dispatch_set_target_queue] QUOTE If you want the system to provide a queue that is appropriate for the current object UNQUOTE
[dispatch_queue_create_with_target] QUOTE Specify DISPATCH_TARGET_QUEUE_DEFAULT to set the target queue to the default type for the current dispatch queue.UNQUOTE
[Dispatch>DispatchQueue>init] QUOTE Specify DISPATCH_TARGET_QUEUE_DEFAULT if you want the system to provide a queue that is appropriate for the current object. UNQUOTE
What is the difference between passing target queue as 'nil' vs 'DISPATCH_TARGET_QUEUE_DEFAULT' to DispatchQueue init?
[Custom Queue][Target Queue concept] [dispatch_set_target_queue] QUOTE The system doesn't allocate threads to the dispatch queue if it has a target queue, unless that target queue is a global concurrent queue. UNQUOTE
The system does allocate threads to the custom dispatch queues that have global concurrent queue as the default target.
What does that mean? Why does targetting to global concurrent queues mean in that case?
[System / GCD Thread Pool] that excutes work items from DispatchQueue: Is this thread pool per queue? or across queues per process? or across processes per device?
I'm looking into a newer XPC API available starting with macOS 14. Although it's declared as a low-level API I can't figure it how to specify code signing requirement using XPCListener and XPCSession. How do I connect it with xpc_listener_set_peer_code_signing_requirement and xpc_connection_set_peer_code_signing_requirement which require xpc_listener_t and xpc_connection_t respectively?
Foundation XPC is declared as a high-level API and provides easy ways to specify code signing requirements on both ends of xpc.
I'm confused with all these XPC APIs and their future:
Newer really high-level XPCListener and XPCSession API (in low-level framework???)
Low-level xpc_listener_t & xpc_connection_t -like API. Is it being replaced by newer XPCListener and XPCSession?
How is it related to High-level Foundation XPC? Are NSXPCListener and NSXPCConnection going to be deprecated and replaced by XPCListener and XPCSession??
Hello everyone!
I'm having a problem with background tasks running in the foreground.
When a user enters the app, a background task is triggered. I've written some code to check if the app is in the foreground and to prevent the task from running, but it doesn't always work. Sometimes the task runs in the background as expected, but other times it runs in the foreground, as I mentioned earlier.
Could it be that I'm doing something wrong? Any suggestions would be appreciated.
here is code:
class BackgroundTaskService {
@Environment(\.scenePhase) var scenePhase
static let shared = BackgroundTaskService()
private init() {}
// MARK: - create task
func createCheckTask() {
let identifier = TaskIdentifier.check
BGTaskScheduler.shared.getPendingTaskRequests { requests in
if requests.contains(where: { $0.identifier == identifier.rawValue }) {
return
}
self.createByInterval(identifier: identifier.rawValue, interval: identifier.interval)
}
}
private func createByInterval(identifier: String, interval: TimeInterval) {
let request = BGProcessingTaskRequest(identifier: identifier)
request.earliestBeginDate = Date(timeIntervalSinceNow: interval)
scheduleTask(request: request)
}
// MARK: submit task
private func scheduleTask(request: BGProcessingTaskRequest) {
do {
try BGTaskScheduler.shared.submit(request)
} catch {
// some actions with error
}
}
// MARK: background actions
func checkTask(task: BGProcessingTask) {
let today = Calendar.current.startOfDay(for: Date())
let lastExecutionDate = UserDefaults.standard.object(forKey: "lastCheckExecutionDate") as? Date ?? Date.distantPast
let notRunnedToday = !Calendar.current.isDate(today, inSameDayAs: lastExecutionDate)
guard notRunnedToday else {
task.setTaskCompleted(success: true)
createCheckTask()
return
}
if scenePhase == .background {
TaskActionStore.shared.getAction(for: task.identifier)?()
}
task.setTaskCompleted(success: true)
UserDefaults.standard.set(today, forKey: "lastCheckExecutionDate")
createCheckTask()
}
}
And in AppDelegate:
BGTaskScheduler.shared.register(forTaskWithIdentifier: "check", using: nil) { task in
guard let task = task as? BGProcessingTask else { return }
BackgroundTaskService.shared.checkNodeTask(task: task)
}
BackgroundTaskService.shared.createCheckTask()
I'm working on an enterprise product that's mainly a daemon (with Endpoint Security) without any GUI component. I'm looking into the update process for daemons/agents that was introduced with Ventura (Link), but I have to say that the entire process is just deeply unfun. Really can't stress this enough how unfun.
Anyway...
The product bundle now contains a dedicated Swift executable that calls SMAppService.register for both the daemon and agent.
It registers the app in the system preferences login items menu, but I also get an error.
Error registering daemon: Error Domain=SMAppServiceErrorDomain Code=1 "Operation not permitted" UserInfo={NSLocalizedFailureReason=Operation not permitted}
What could be the reason?
I wouldn't need to activate the items, I just need them to be added to the list, so that I can control them via launchctl.
Which leads me to my next question, how can I control bundled daemons/agents via launchctl? I tried to use launchctl enable and bootstrap, just like I do with daemons under /Library/LaunchDaemons, but all I get is
sudo launchctl enable system/com.identifier.daemon
sudo launchctl bootstrap /Path/to/daemon/launchdplist/inside/bundle/Library/LaunchDaemons/com.blub.plist
Bootstrap failed: 5: Input/output error (not super helpful error message)
I'm really frustrated by the complexity of this process and all of its pitfalls.
Hello,
I am currently developing an iOS application using SensorKit. I encountered an issue when attempting to fetch SensorKit data in the background using background tasks (appRefresh, processing). The following error occurs:
In the delegate function func sensorReader(_ reader: SRSensorReader, fetching fetchRequest: SRFetchRequest, failedWithError error: any Error) {}, I receive the error:
SRErrorDataInaccessible.
In code specific manner:
start and handle background fetch (appRefresh)
func handleAppRefreshTask(task: BGAppRefreshTask) {
logger.logWithServer(level: .default, message: "background fetch start", category: String(describing: BackgroundTaskManager.self))
scheduleBackgroundFetch()
let queue = OperationQueue()
queue.maxConcurrentOperationCount = 1
let fetchOperation = FetchOperation()
queue.addOperation(fetchOperation)
task.expirationHandler = {
self.logger.logWithServer(level: .error, message: "background fetch expirated", category: String(describing: BackgroundTaskManager.self))
queue.cancelAllOperations()
}
fetchOperation.completionBlock = {
task.setTaskCompleted(success: !fetchOperation.isCancelled)
}
}
Background fetch operation class
class FetchOperation: Operation {
override func main() {
guard !isCancelled else { return }
Task {
// this function will execute fetch request for all user allowed sensorReader, 'func fetch(_ request: SRFetchRequest)'
await SensorkitManager.shared.startFetchAndUpload()
}
}
}
I have the following questions:
Is it possible to fetch SensorKit data in the background?
If it is possible, why does the above error occur?
If it is possible, could you provide the solution code and the correct workflow to avoid this error?
Thank you.
Let's image that someone wants to use a background service to keep track of FSEvents activity, at the file level (a firehose, some might say).
I choose this example, to indicate the volume and rate of data transmission in question. I'm not creating a front-end for FSEvents data, but my background service may generate data at a similar pace. The service runs off of user defined document/s that specify the FSEvent background filtering to be applied. Those that match get stored into a database. But filters can match on almost all the data being emitted by FSEvents.
The user decides to check on the service's activity and database writes by launching a GUI that sends requests to the background service using XPC. So the GUI can request historic data from a database, but also get a real-time view of what FS events the service is busy filtering.
So it's a client-server approach, that's concerned with monitoring an event stream over XPC. I understand XPC is a request/response mechanism, and I might look into using a reverse connection here, but my main concern is one of performance. Is XPC capable of coping with such a high volume of data transmision? Could it cope with 1000s of rows of table data updates per second sent to a GUI frontend?
I know there are streaming protocol options that involve a TCP connection, but I really want to stay away from opening sockets.
I've been experimenting with the new low-level Swift API for XPC (XPCSession and XPCListener). The ability to send and receive Codable messages is an appealing alternative to making an @objc protocol in order to use NSXPCConnection from Swift — I can easily create an enum type whose cases map onto the protocol's methods.
But our current XPC code validates the incoming connection using techniques similar to those described in Quinn's "Apple Recommended" response to the "Validating Signature Of XPC Process" thread. I haven't been able to determine how to do this with XPCListener; neither the documentation nor the Swift interface have yielded any insight.
The Creating XPC Services article suggests using Xcode's XPC Service template, which contains this code:
let listener = try XPCListener(service: serviceName) { request in
request.accept { message in
performCalculation(with: message)
}
}
The apparent intent is to inspect the incoming request and decide whether to accept it or reject it, but there aren't any properties on IncomingSessionRequest that would allow the service to make that decision. Ideally, there would be a way to evaluate a code signing requirement, or at least obtain the audit token of the requesting process.
(I did notice that a function xpc_listener_set_peer_code_signing_requirement was added in macOS 14.4, but it takes an xpc_listener_t argument and I can't tell whether XPCListener is bridged to that type.)
Am I missing something obvious, or is there a gap in the functionality of XPCListener and IncomingSessionRequest?
Swift Concurrency Resources:
Forums tags: Concurrency
The Swift Programming Language > Concurrency documentation
Migrating to Swift 6 documentation
WWDC 2022 Session 110351 Eliminate data races using Swift Concurrency — This ‘sailing on the sea of concurrency’ talk is a great introduction to the fundamentals.
WWDC 2021 Session 10134 Explore structured concurrency in Swift — The table that starts rolling out at around 25:45 is really helpful.
Swift Async Algorithms package
Swift Concurrency Proposal Index DevForum post
Why is flow control important? forums post
Dispatch Resources:
Forums tags: Dispatch
Dispatch documentation — Note that the Swift API and C API, while generally aligned, are different in many details. Make sure you select the right language at the top of the page.
Dispatch man pages — While the standard Dispatch documentation is good, you can still find some great tidbits in the man pages. See Reading UNIX Manual Pages. Start by reading dispatch in section 3.
WWDC 2015 Session 718 Building Responsive and Efficient Apps with GCD [1]
WWDC 2017 Session 706 Modernizing Grand Central Dispatch Usage [1]
Avoid Dispatch Global Concurrent Queues forums post
Waiting for an Async Result in a Synchronous Function forums post
Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
[1] These videos may or may not be available from Apple. If not, the URL should help you locate other sources of this info.
When my app enter to background, I start a background task, and when Expiration happens, I end my background task. The code likes below:
backgroundTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
if (backgroundTask != UIBackgroundTaskInvalid) {
[[UIApplication sharedApplication] endBackgroundTask:backgroundTask];
backgroundTask = UIBackgroundTaskInvalid;
[self cancel];
}
});
}];
When the breakpoint is triggered at the endBackgroundTask line, I also get the following log:
[BackgroundTask] Background task still not ended after expiration handlers were called: <UIBackgroundTaskInfo: 0x282d7ab40>: taskID = 36, taskName = Called by MyApp, from MyMethod, creationTime = 892832 (elapsed = 26). This app will likely be terminated by the system. Call UIApplication.endBackgroundTask(:) to avoid this.
The log don't appear every time, so why is that? Is there something wrong with my code?
XPC is the preferred inter-process communication (IPC) mechanism on Apple platforms. XPC has three APIs:
The high-level NSXPCConnection API, for Objective-C and Swift
The low-level Swift API, introduced with macOS 14
The low-level C API, which, while callable from all languages, works best with C-based languages
General:
Forums subtopic: App & System Services > Processes & Concurrency
Forums tag: XPC
Creating XPC services documentation
NSXPCConnection class documentation
Low-level API documentation
XPC has extensive man pages — For the low-level API, start with the xpc man page; this is the original source for the XPC C API documentation and still contains titbits that you can’t find elsewhere. Also read the xpcservice.plist man page, which documents the property list format used by XPC services.
Daemons and Services Programming Guide archived documentation
WWDC 2012 Session 241 Cocoa Interprocess Communication with XPC — This is no longer available from the Apple Developer website )-:
Technote 2083 Daemons and Agents — It hasn’t been updated in… well… decades, but it’s still remarkably relevant.
TN3113 Testing and Debugging XPC Code With an Anonymous Listener
XPC and App-to-App Communication forums post
Validating Signature Of XPC Process forums post
This forums post summarises the options for bidirectional communication
This forums post explains the meaning of privileged flag
Related tags include:
Inter-process communication, for other IPC mechanisms
Service Management, for installing and uninstalling Service Management login items, launchd agents, and launchd daemons
Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
Service Management framework supports installing and uninstalling services, including Service Management login items, launchd agents, and launchd daemons.
General:
Forums subtopic: App & System Services > Processes & Concurrency
Forums tag: Service Management
Service Management framework documentation
Daemons and Services Programming Guide archived documentation
Technote 2083 Daemons and Agents — It hasn’t been updated in… well… decades, but it’s still remarkably relevant.
EvenBetterAuthorizationSample sample code — This has been obviated by SMAppService.
SMJobBless sample code — This has been obviated by SMAppService.
Sandboxing with NSXPCConnection sample code
WWDC 2022 Session 10096 What’s new in privacy introduces the new SMAppService facility, starting at 07˸07
BSD Privilege Escalation on macOS forums post
Getting Started with SMAppService forums post
Background items showing up with the wrong name forums post
Related forums tags include:
XPC, Apple’s preferred inter-process communication (IPC) mechanism
Inter-process communication, for other IPC mechanisms
Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
This week I’m handling a DTS incident from a developer who wants to escalate privileges in their app. This is a tricky problem. Over the years I’ve explained aspects of this both here on DevForums and in numerous DTS incidents. Rather than do that again, I figured I’d collect my thoughts into one place and share them here.
If you have questions or comments, please start a new thread with an appropriate tag (Service Management or XPC are the most likely candidates here) in the App & System Services > Core OS topic area.
Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
BSD Privilege Escalation on macOS
macOS has multiple privilege models. Some of these were inherited from its ancestor platforms. For example, Mach messages has a capability-based privilege model. Others were introduced by Apple to address specific user scenarios. For example, macOS 10.14 and later have mandatory access control (MAC), as discussed in On File System Permissions.
One of the most important privilege models is the one inherited from BSD. This is the classic users and groups model. Many subsystems within macOS, especially those with a BSD heritage, use this model. For example, a packet tracing tool must open a BPF device, /dev/bpf*, and that requires root privileges. Specifically, the process that calls open must have an effective user ID of 0, that is, the root user. That process is said to be running as root, and escalating BSD privileges is the act of getting code to run as root.
IMPORTANT Escalating privileges does not bypass all privilege restrictions. For example, MAC applies to all processes, including those running as root. Indeed, running as root can make things harder because TCC will not display UI when a launchd daemon trips over a MAC restriction.
Escalating privileges on macOS is not straightforward. There are many different ways to do this, each with its own pros and cons. The best approach depends on your specific circumstances.
Note If you find operations where a root privilege restriction doesn’t make sense, feel free to file a bug requesting that it be lifted. This is not without precedent. For example, in macOS 10.2 (yes, back in 2002!) we made it possible to implement ICMP (ping) without root privileges. And in macOS 10.14 we removed the restriction on binding to low-number ports (r. 17427890). Nice!
Decide on One-Shot vs Ongoing Privileges
To start, decide whether you want one-shot or ongoing privileges. For one-shot privileges, the user authorises the operation, you perform it, and that’s that. For example, if you’re creating an un-installer for your product, one-shot privileges make sense because, once it’s done, your code is no longer present on the user’s system.
In contrast, for ongoing privileges the user authorises the installation of a launchd daemon. This code always runs as root and thus can perform privileged operations at any time.
Folks often ask for one-shot privileges but really need ongoing privileges. A classic example of this is a custom installer. In many cases installation isn’t a one-shot operation. Rather, the installer includes a software update mechanism that needs ongoing privileges. If that’s the case, there’s no point dealing with one-shot privileges at all. Just get ongoing privileges and treat your initial operation as a special case within that.
Keep in mind that you can convert one-shot privileges to ongoing privileges by installing a launchd daemon.
Just Because You Can, Doesn’t Mean You Should
Ongoing privileges represent an obvious security risk. Your daemon can perform an operation, but how does it know whether it should perform that operation?
There are two common ways to authorise operations:
Authorise the user
Authorise the client
To authorise the user, use Authorization Services. For a specific example of this, look at the EvenBetterAuthorizationSample sample code.
Note This sample hasn’t been updated in a while (sorry!) and it’s ironic that one of the things it demonstrates, opening a low-number port, no longer requires root privileges. However, the core concepts demonstrated by the sample are still valid.
The packet trace example from above is a situation where authorising the user with Authorization Services makes perfect sense. By default you might want your privileged helper tool to allow any user to run a packet trace. However, your code might be running on a Mac in a managed environment, where the site admin wants to restrict this to just admin users, or just a specific group of users. A custom authorisation right gives the site admin the flexibility to configure authorisation exactly as they want.
Authorising the client is a relatively new idea. It assumes that some process is using XPC to request that the daemon perform a privileged operation. In that case, the daemon can use XPC facilities to ensure that only certain processes can make such a request.
Doing this securely is a challenge. For specific API advice, see this post.
WARNING This authorisation is based on the code signature of the process’s main executable. If the process loads plug-ins [1], the daemon can’t tell the difference between a request coming from the main executable and a request coming from a plug-in.
[1] I’m talking in-process plug-ins here. Plug-ins that run in their own process, such as those managed by ExtensionKit, aren’t a concern.
Choose an Approach
There are (at least) seven different ways to run with root privileges on macOS:
A setuid-root executable
The sudo command-line tool
The authopen command-line tool
AppleScript’s do shell script command, passing true to the administrator privileges parameter
The osascript command-line tool to run an AppleScript
The AuthorizationExecuteWithPrivileges routine, deprecated since macOS 10.7
The SMJobSubmit routine targeting the kSMDomainSystemLaunchd domain, deprecated since macOS 10.10
The SMJobBless routine, deprecated since macOS 13
An installer package (.pkg)
The SMAppService class, a much-needed enhancement to the Service Management framework introduced in macOS 13
Note There’s one additional approach: The privileged file operation feature in NSWorkspace. I’ve not listed it here because it doesn’t let you run arbitrary code with root privileges. It does, however, have one critical benefit: It’s supported in sandboxed apps. See this post for a bunch of hints and tips.
To choose between them:
Do not use a setuid-root executable. Ever. It’s that simple! Doing that is creating a security vulnerability looking for an attacker to exploit it.
If you’re working interactively on the command line, use sudo, authopen, and osascript as you see fit.
IMPORTANT These are not appropriate to use as API. Specifically, while it may be possible to invoke sudo programmatically under some circumstances, by the time you’re done you’ll have code that’s way more complicated than the alternatives.
If you’re building an ad hoc solution to distribute to a limited audience, and you need one-shot privileges, use either AuthorizationExecuteWithPrivileges or AppleScript.
While AuthorizationExecuteWithPrivileges still works, it’s been deprecated for many years. Do not use it in a widely distributed product.
The AppleScript approach works great from AppleScript, but you can also use it from a shell script, using osascript, and from native code, using NSAppleScript. See the code snippet later in this post.
If you need one-shot privileges in a widely distributed product, consider using SMJobSubmit. While this is officially deprecated, it’s used by the very popular Sparkle update framework, and thus it’s unlikely to break without warning.
If you only need escalated privileges to install your product, consider using an installer package. That’s by far the easiest solution to this problem.
Keep in mind that an installer package can install a launchd daemon and thereby gain ongoing privileges.
If you need ongoing privileges but don’t want to ship an installer package, use SMAppService. If you need to deploy to older systems, use SMJobBless.
For instructions on using SMAppService, see Updating helper executables from earlier versions of macOS.
For a comprehensive example of how to use SMJobBless, see the EvenBetterAuthorizationSample sample code. For the simplest possible example, see the SMJobBless sample code. That has a Python script to help you debug your setup. Unfortunately this hasn’t been updated in a while; see this thread for more.
Hints and Tips
I’m sure I’ll think of more of these as time goes by but, for the moment, let’s start with the big one…
Do not run GUI code as root. In some cases you can make this work but it’s not supported. Moreover, it’s not safe. The GUI frameworks are huge, and thus have a huge attack surface. If you run GUI code as root, you are opening yourself up to security vulnerabilities.
Appendix: Running an AppleScript from Native Code
Below is an example of running a shell script with elevated privileges using NSAppleScript.
WARNING This is not meant to be the final word in privilege escalation. Before using this, work through the steps above to see if it’s the right option for you.
Hint It probably isn’t!
let url: URL = … file URL for the script to execute …
let script = NSAppleScript(source: """
on open (filePath)
if class of filePath is not text then
error "Expected a single file path argument."
end if
set shellScript to "exec " & quoted form of filePath
do shell script shellScript with administrator privileges
end open
""")!
// Create the Apple event.
let event = NSAppleEventDescriptor(
eventClass: AEEventClass(kCoreEventClass),
eventID: AEEventID(kAEOpenDocuments),
targetDescriptor: nil,
returnID: AEReturnID(kAutoGenerateReturnID),
transactionID: AETransactionID(kAnyTransactionID)
)
// Set up the direct object parameter to be a single string holding the
// path to our script.
let parameters = NSAppleEventDescriptor(string: url.path)
event.setDescriptor(parameters, forKeyword: AEKeyword(keyDirectObject))
// The `as NSAppleEventDescriptor?` is required due to a bug in the
// nullability annotation on this method’s result (r. 38702068).
var error: NSDictionary? = nil
guard let result = script.executeAppleEvent(event, error: &error) as NSAppleEventDescriptor? else {
let code = (error?[NSAppleScript.errorNumber] as? Int) ?? 1
let message = (error?[NSAppleScript.errorMessage] as? String) ?? "-"
throw NSError(domain: "ShellScript", code: code, userInfo: nil)
}
let scriptResult = result.stringValue ?? ""
Revision History
2025-03-24 Added info about authopen and osascript.
2024-11-15 Added info about SMJobSubmit. Made other minor editorial changes.
2024-07-29 Added a reference to the NSWorkspace privileged file operation feature. Made other minor editorial changes.
2022-06-22 First posted.
General:
Forums subtopic: App & System Services > Processes & Concurrency
Forums tag: Background Tasks
Background Tasks framework documentation
UIApplication background tasks documentation
ProcessInfo expiring activity documentation
Using background tasks documentation for watchOS
Performing long-running tasks on iOS and iPadOS documentation
WWDC 2020 Session 10063 Background execution demystified — This is critical resource. Watch it! [1]
WWDC 2022 Session 10142 Efficiency awaits: Background tasks in SwiftUI
WWDC 2025 Session 227 Finish tasks in the background — This contains an excellent summary of the expected use cases for each of the background task types.
iOS Background Execution Limits forums post
UIApplication Background Task Notes forums post
Testing and Debugging Code Running in the Background forums post
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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
[1] Sadly the video is currently not available from Apple. I’ve left the link in place just in case it comes back.
Our app will launch automatically in the background,Doubt is the result of background fetch ,so we cancel the background modes setting of the background fetch,but we still can see the performFetchWithCompletionHandler method called when app launch in the background。Background launch will cause some bugs in our app. We don't want the app to start in the background. We hope to get help