[diacritical]

Unfortunately from what I read a couple of times, including a month or so ago, GrapheneOS discourages and doesn't support rooting the phone for security reasons that seem vague to me and don't appeal to my need to actually own my phone and OS. You could still root it with some third party tools from what I know, but not having root as the default makes it less of a secure FOSS OS and more of a closed down toy.

As for payment apps and other crap that refuses to run if I, the owner and administrator of my own device, don't have admin access, I would just refuse to run it. What's next - websites refusing to work if I have root on my Linux desktop?

[strcat]

LineageOS also discourages and doesn't support replacing the core of the OS with a rootkit providing persistent app accessible root. GrapheneOS is no different from LineageOS in that regard. People do this with GrapheneOS regardless of our strong recommendation not do it. Our reasons for discouraging it aren't vague. It very directly harms the security model and is not a good approach to implementing any of the features hacked together through it. Those features should be properly implemented to fit within the overall approach taken by GrapheneOS. Giving root access to a huge portion of the OS harms security even if you never use the feature. It does not mean you can't do it, we only recommend you don't.

[Narushia]

I agree that the features should ideally be provided by the base system so that the user does not have to "hack them in" with root-powered apps. But the reality is that most Android "distros" simply do not support the features that I would consider basic functionality. I mainly root for three reasons:

- Backing up all app data via Neo Backup. Android has an auto-backup feature that backs up app data to the user's Google Drive, but unfortunately the app developer can simply opt out of this, and the user cannot do anything about it. This means that app data may be lost when migrating to a new phone, as the app data is stored in directories that are not accessible in the filesystem without root.

- High-quality call recording via Call Recorder. For some reason, some (most?) phones do not allow apps to access the raw incoming audio stream. Non-root apps have to rely on capturing the other end through the microphone, which is horrible.

- /etc/hosts-based ad blocking while using a VPN via AdAway. DNS-based ad blocking is possible via apps like AdGuard, which use a local VPN to accomplish this. Unfortunately, Android only allows one VPN connection at a time, which means that without root I would not be able to use a VPN for any other purpose while simultaneously blocking ads.

---

I have no experience with GrapheneOS, so I'd be interested to hear if these features are possible on it without rooting. If not, can I request these features somewhere?

[Andromxda]

Rooting is a very bad idea. https://madaidans-insecurities.github.io/android.html#rootin... But GrapheneOS is fully open source and provides great build instructions, so you can always make your own build and add whatever features or privileged apps you like within the standard AOSP frameworks for privileged apps with system integration.

> Backing up all app data via Neo Backup

GrapheneOS includes Seedvault by default. https://grapheneos.org/features#encrypted-backups

> High-quality call recording via Call Recorder

Call recording is built into the Dialer app on GrapheneOS. https://grapheneos.org/features#encrypted-backups:~:text=Cal....

> DNS-based ad blocking is possible via apps like AdGuard

DNS-based blocking can also be accomplished by using Android's native Private DNS feature with a resolver that blocks ads. You could even host your own on a VPS if you are more comfortable running name resolution and DNS-level adblocking on infrastructure you control.

The RethinkDNS app also lets you use DNS-level adblocking and a VPN at the same time. https://grapheneos.org/faq#ad-blocking-apps

> I have no experience with GrapheneOS, so I'd be interested to hear if these features are possible on it without rooting.

I recommend giving https://grapheneos.org/features a read.

> If not, can I request these features somewhere?

Check out the issue tracker on GitHub: https://github.com/GrapheneOS/os-issue-tracker/issues

[Narushia]

Thank you so much for replying! Seems promising, I will take a closer look. I'm definitely looking forward to possibly buying a Graphene-powered Motorola phone in the future.

[thot_experiment]

Rooting is only a bad idea if there is an alternative. Unfortunately I have to root my devices because there isn't an alternative method to provide me, the physical owner of the device with control over the device. I would much prefer not to generally have root on my phone but to be able to access root externally or via a hardware switch or some other scheme. ADB root is fine.

The alternative to "running as root" isn't "not having access to root".

[thunderfork]

>Rooting is only a bad idea if there is an alternative.

An alternative to accomplish what?

>to provide me, the physical owner of the device with control over the device

Control over what properties or behaviours of the device, exactly?

No offense, but these complaints feel more like aesthetic ("I want to log into a user named root") than practical ("I want to be able to do things that could only be done under root")

[thot_experiment]

You're missing the point completely, of course there are more secure ways to do a lot of things, the problem is that if there isn't an alternative "secure" mechanism to accomplish what I want if I have root I can just get it done whatever way works for me. I do not want to run into a situation like I did prior to having root, where my voice memos unbeknownst to me end up in some sort of elevated privileged enclave and I can't copy them over to my computer.

There's a myriad of reasons to have root, like baseline I want to be able to watch my network traffic. I want to be able to spoof my location, I want to be able to sftp into my phone and mount it as a drive because it's convenient. I want to access sensors and log them in the background. I wanna just run normal linux daemons.

I don't need any of these reasons though, all I need is the desire to be the ultimate arbiter of what happens on my devices. I don't need to or want to control all aspects of what goes on my device, I'm fine giving up control, I'm not fine with it being taken away from me. Everything else is secondary, the person with final say on what happens on my device should be me.

[diacritical]

> https://madaidans-insecurities.github.io/android.html#rootin...

I'm trying to understand why rooting Android is such a sin.

If I give root to my terminal so I can browse and edit any files I want, I'm placing a lot of trust in the terminal, sure. But trusting the terminal seems reasonable, as it's an important (basic; fundamental; necessary) part of any "real" OS. If I don't trust the terminal to not be malicious, why should I trust my OS? Anything could be compromised from a supply-chain attack. If we don't trust anything, we can turn off the computer and have perfect security, but if we accept that there's a trade-off between security and usability, we have to place some trust in some parts of the system.

> It does not matter if you have to whitelist apps that have root — an attacker can fake user input by, for example, clickjacking, or they can exploit vulnerabilities in apps that you have granted root to. Rooting turns huge portions of the operating system into root attack surface; vulnerabilities in the UI layer — such as in the display server, among other things — can now be abused to gain complete root access.

So if some app can somehow exploit the display server, it can inject commands on the terminal and hide the real output? I know the X server on Linux has (or has had) major security issues [1] that don't provide any real GUI isolation. Is that the type of issues Madaidan is talking about?

I don't know much about Android's display server, but if it's possible for an app without root access to exploit it, couldn't that app inject touch events or keystrokes in another app, or read the other app's screen? How would not having root benefit me if a random can view or control other apps without my knowledge by exploiting the display server? [2]

From what I gather if an app with root access has vulnerabilities, it makes it easier for another app (or other type of malicious code) to use it to gain root. But if the UI layer, to use Madaidan's example, has a vulnerability, it seems like it could be exploited successfully, with awful consequences, even if the malicious code doesn't get root in the end. So if I choose several apps to give root access to, I would just extend the attack surface from {all of the OS and its various layers} to {all of the OS and its various layers and those several apps}.

> root fundamentally breaks verified boot and other security features by placing excessive trust in persistent state.

I don't understand this. Could someone explain it with more details to me, please?

[1] https://theinvisiblethings.blogspot.com/2011/04/linux-securi...

[2] https://xkcd.com/1200/

[Andromxda]

Of course the topic as a whole is much more complex than that, but I'll try to summarize it. Android has 3 systems of access control [1][2]:

- Discretionary Access Control, i.e. the standard Unix file permissions

- Mandatory Access Control, implemented in the form of the SELinux and YAMA LSMs (GrapheneOS stopped using YAMA in the 2024031400 release and replaced it with advanced SELinux policies)

- Android permissions which have to be disclosed in the AndroidManifest.xml, and most of the time need to be granted by the user at runtime

Root simply bypasses ALL of these security mechanisms. This is a clear violation of the principle of least privilege, since most of the stuff you are doing with root probably doesn't require access to your entire filesystem, and could easily run within an SELinux context. But writing and deploying a modified SELinux policy would take extra time and effort, and devs are lazy, so they just use root to completely bypass it.

As madaidan points out, only a tiny subset of system processes on Android run as root. [3] And Android has clear guidelines about what root process are and aren't allowed to do. From the AOSP documentation:

> Where possible, root code should be isolated from untrusted data and accessed via IPC.

> Root processes must not listen on a network socket.

> Root processes must not provide a general-purpose runtime for apps (for example, a Java VM).

Desktop systems are very different from Android and iOS. Out of Android's three major security mechanisms, they typically only implement one. This is why ransomware is so insanely successful. Every program has access to all the files and folders of the logged in user, including network shares, etc. Even on systems that implement application sandboxing and a permission system, such as macOS, it's only an afterthought, and isn't enforced properly. (macOS is still miles ahead of Windows and Linux though) For example, when installing a 3rd-party terminal emulator such as iTerm2 on macOS, you have to grant it the permission to access your entire file system (otherwise you will be limited to the home directory IIRC). But this permission also applies recursively to every process started within the terminal, greatly limiting its usefulness.

> I don't understand this. Could someone explain it with more details to me, please?

Android uses Verified Boot to protect against both Evil maid attacks [4], i.e. someone modifying the operating system on the hard drive, and malware persistence. By default, the Android /system partition is mounted in read-only mode, unlike for example your C:\Windows directory, or system directories like /bin on Linux. This prevents malware from modifying the operating system. If you ever get malware on Android or iOS, in most cases you can get rid of it, by simply rebooting your device. Unless of course, the malware has some persistence mechanism. Root obviously provides a great vector for persistence, since the system partition could simply be remounted in a writable mode, and the system could be modified however the attacker wants to.

When you build your own copy of AOSP or GrapheneOS, include your modifications, and sign the image with your own Verified Boot keys, that image can't be modified or tampered with by an attacker. It's perfectly secure to do that (of course only if you can trust the extra code you're including).

[1] https://source.android.com/docs/security/app-sandbox#protect...

[2] https://arxiv.org/pdf/1904.05572

[3] https://source.android.com/docs/security/overview/implement#...

[4] https://en.wikipedia.org/wiki/Evil_maid_attack

[diacritical]

Thanks a lot for the thorough reply!

I'll read the links you posted a bit later, but for now I have a few questions that could help me clear some misconceptions I might have. I haven't used a rooted Android device yet, so I might be wrong about how it works. I've read about magisk and other methods a bit and am at familiar with the security concepts you wrote.

Let's say I give root permissions to a terminal app TermGood and I don't give root permissions to an app GameEvil. I trust TermGood fully - I accept that if TermGood is malicious or if it has some exploitable bugs, it's game over. I don't trust GameEvil at all, but I trust the OS to limit the damage it could do since it doesn't have root permissions.

1. Could I run TermGood with root only sometimes? Run it with root, close it, then run it with the normal restricted permissions. That's just to clarify how rooting works in general.

2. For MacOS you wrote "this permission also applies recursively to every process started within the terminal, greatly limiting its usefulness.". For Android, if I run a program like ls or vi from TermGood, will it be launched with root permissions, too? Will I have fully trust that ls or vi are not malicious or exploitable in certain ways (e.g., running vi on a file created by GameEvil that exploits vi).

3. Will GameEvil have any way to compromise the OS, to circumvent some security boundaries or to do any other damage it wouldn't have been able to do if I hadn't "rooted" the OS?

3.1. Would GameEvil be able to launch TermGood on its own without my knowledge? Or somehow piggyback on TermGood to take advantage of its root permissions?

3.2. If there's a bug in the UI layer (the "display server" - what Madaidan gave as an example) and I had TermGood open as root, GameEvil could inject some keystrokes into TermGood to read its screen (like the output of a cat command, for example).

3.3. Just because TermGood could have root access, does that somehow make GameEvil more likely to gain root access itself? On Linux, if there is sudo installed, it might increase the attack surface because sudo might have exploitable bugs. What could GameEvil exploit?

4. If I don't root my OS by any of the available means, what would my alternatives be for full control and customization?

4.1. AFAIK with adb you don't get rw access on / if the OS is not rooted.

4.2. Let's say I want to X (e.g., backup / to a server when it commands it to) without rooting. Would I have to create the app, then modify security policies in a way that would enable it to run without root, but with granular permissions for X specifically and nothing else, like permissions to read / and to listen on a network socket, maybe by changing the SELinux policies and/or the Android permissions of the app? Or would that be impossible? I don't really have a specific X in mind, but I want X to be as broad as possible. That's what makes it a real OS for me - being able to do anything on it.

5. If TermGood is compromised, it could reinfect the root filesystem after booting and effectively bypass Verified Boot. Or, if I used TermGood to change something on /, e.g. `touch /testfile`, would I be able to sign the new root filesystem? Ideally I should be able to control all the keys and sign the whole chain of trust whenever I make a change.

6. Android doesn't have FDE, so evil maid seems relatively easy (although any unrestricted physical access to the device should be treated extremely seriously, even with FDE in place). Is that correct?

Basically, if we assume that:

* I fully trust TermGood and the processes it spawns to not be malicious or have exploitable bugs;

* I could resign any changes I've made so I can keep Verified Boot working.

Then, would I be able to give TermGood root and keep my security?

[gruez]

>but not having root as the default makes it less of a secure FOSS OS and more of a closed down toy.

I don't get it, it's "less of a secure FOSS OS" to not have root by default, but it's secure to run random apps as root and breaking android's security model? What's the threat model here?

[treyd]

Those "random apps" are foss terminal emulators and other various foss apps I explicitly installed.

[gruez]

So what's wrong with using avbroot or magisk to root?

[kevincox]

Yeah, this is the deal breaker for me as well. The fact that I own my device is non-negotiable. It is the reason I left the stock OS and I'm not going back. The idea that I can't access my own files if an app doesn't explicitly give me access is wild to me. I understand there are security risks of a root permission but it is important to have that fallback when you need it and the existing permissions aren't sufficient.

[thot_experiment]

The "access your own files" thing is so insane! Hard to describe my feelings [negative] when I found out that all of my voice notes were in the voice recorder and the easiest way to get them out was to manually send each one to myself over discord. Google helpfully mentions that you can just "download them through google takeout" and doesn't leave any option for people who don't just give all their personal data to google.

[MSFT_Edging]

I use a FOSS voice recorder app from F-Droid. It's just called "Voice Recorder" with an orange icon. It does exactly what it says, records audio from your microphone, lets you play them back. They're just files on the device.

Anytime I need a "simple" utility, I check f-droid first to get the one-trick-pony app over spyware from the play store.

Other utilities I use are: WorkTimer: pomodoro app DiskUsage: self explanatory Http Request Shortcuts: setup home screen app shortcuts that run http requests

[thot_experiment]

Yeah I swapped to using the f-droid version after that debacle, though the one i use has a green icon. XD

[strcat]

LineageOS also discourages and doesn't support replacing the core of the OS with a rootkit providing persistent app accessible root. GrapheneOS is no different from LineageOS in that regard. People do this with GrapheneOS regardless of our strong recommendation not do it. Our reasons for discouraging it aren't vague. It very directly harms the security model and is not a good approach to implementing any of the features hacked together through it. Those features should be properly implemented to fit within the overall approach taken by GrapheneOS. Giving root access to a huge portion of the OS harms security even if you never use the feature. It does not mean you can't do it, we only recommend you don't.

[kevincox]

LineageOS provides ADB root access in stock builds. Sure, it isn't as convenient as some su apps but at least I can use ADB to access every file on the device. It probably also improves the attack surface compared to a su app.

> It very directly harms the security model

What do you mean by this? You mean that it is a "god permission" that bypasses other permissions? If so then yes, with great power comes great responsibility and it shouldn't be used lightly.

> and is not a good approach to implementing any of the features hacked together through it.

Maybe not, but is there an alternative? What is your recommended way to access all files of any app? This is my primary use case. Modification would also be valuable but I would be ok with read-only access.

> Giving root access to a huge portion of the OS harms security even if you never use the feature.

Can you explain why root access must be given to a huge portion of the OS? Why can't it be limited to specific apps or features (like ADB shell)?

> It does not mean you can't do it, we only recommend you don't.

Of course. It is your right to recommend whatever you want :)

[rudhdb773b]

It's pretty easy to make your own `userdebug` build of GrapheneOS using their official build instructions

That's what I do to get `adb root` and full file system access.

[palata]

> [I want root,] The fact that I own my device is non-negotiable.

I read that a lot, and I agree that I want to own my device. But that does not mean that I should have root access on the OS I choose to install on it.

Owning my device means that I should be able to install whatever OS I want. It does not mean at all that OS developers must do whatever I tell you to do.

[kevincox]

Yes, that is why it is a deal breaker. I'll choose to run a different OS. I didn't say that GrapheneOS must support root. Just that I won't run it if they don't.

[palata]

And I'm fine with you wanting root on the device you own. But you were implying that not having root means that you don't own your device. I disagree with that. You can totally own your device and not be root.

I think it is important, because I read a lot of comments that imply that "owning their device" means "owning the developers". And that's a wrong fight.

The real fight is that it should be illegal to prevent me from installing my preferred OS on a general-purpose computer.

[kevincox]

Fair enough. Owning means having a choice. The unlockable bootloader enables that. But for me the choice of OS will be one that lets me access all files on the device should I need to.

[galangalalgol]

What should that support look like? Maybe have a userdebug build already built and available? I don't include a root account on hardened container images for some of the same reasons they cite. So including it for everyone and creating a way to activate it is suboptimal for people who don't want that trade off. A parallel build pipeline seems the most reasonable to me?

[kevincox]

Yeah, I would be fine with a different build stream. I do think it could be sufficiently secure in a single stream but it will always be increased attack surface so the safest option is to do separate builds.

I also don't include a root account in my container images, but you probably have a root account on the sever that runs them in case you need to debug something. But you can probably also build and deploy a new container. At the end of the day you almost always want some last-resort way to access the data stored in case something goes very wrong. Whether that is for backups, "hostile" data export or for other reasons it is important to me.

[galangalalgol]

I don't actually. Devs don't get root at my employer. Even on a vm. I have rootless podman, and can be root in a container. Even our gitlab instances don't have any privileged runners. So kaneko etc.

[stavros]

Hm, what do you mean? What app has to let you access your files? Is this Graphene-specific?

[strcat]

There's nothing GrapheneOS-specific about it and it doesn't prevent rooting. LineageOS doesn't officially support it any more than GrapheneOS does. It doesn't stop people doing it for either. Our recommendations aren't law.

[kevincox]

Any files created by apps in their main data directories are inaccessible on most distributions of Android (I think it is actually required to be Google certified). The exception is apps that go out of their way to store files in user accessible directories or provide a feature to export or share data out of the app.

By rooting your device you can access the app data directories as you wish.

[stavros]

Ah, you mean /data/data, I see, thanks. I forgot as I've usually had rooted devices (until they stopped Google Pay working).

[subscribed]

These reasons for not supporting the root have been stated on their discussion forum multiple times.

But they do not stop you from doing so, you can fairly easily build your own images with root enabled.