cf9bc8d45f
This makes Chromium use the SVG favicon universally including as the favicon for non-HTML files.
562 lines
39 KiB
HTML
562 lines
39 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="en" prefix="og: https://ogp.me/ns#">
|
|
<head>
|
|
<meta charset="utf-8"/>
|
|
<title>Usage guide | GrapheneOS</title>
|
|
<meta name="description" content="Usage instructions for GrapheneOS, a security and privacy focused mobile OS with Android app compatibility."/>
|
|
<meta name="theme-color" content="#212121"/>
|
|
<meta name="msapplication-TileColor" content="#ffffff"/>
|
|
<meta name="viewport" content="width=device-width, initial-scale=1"/>
|
|
<meta name="twitter:site" content="@GrapheneOS"/>
|
|
<meta name="twitter:creator" content="@GrapheneOS"/>
|
|
<meta property="og:title" content="GrapheneOS usage guide"/>
|
|
<meta property="og:description" content="Usage instructions for GrapheneOS, a security and privacy focused mobile OS with Android app compatibility."/>
|
|
<meta property="og:type" content="website"/>
|
|
<meta property="og:image" content="https://grapheneos.org/opengraph.png"/>
|
|
<meta property="og:image:width" content="512"/>
|
|
<meta property="og:image:height" content="512"/>
|
|
<meta property="og:image:alt" content="GrapheneOS logo"/>
|
|
<meta property="og:site_name" content="GrapheneOS"/>
|
|
<meta property="og:url" content="https://grapheneos.org/usage"/>
|
|
<link rel="canonical" href="https://grapheneos.org/usage"/>
|
|
<link rel="icon" href="/favicon.ico"/>
|
|
<link rel="icon" sizes="any" type="image/svg+xml" href="/favicon.svg"/>
|
|
<link rel="mask-icon" href="/mask-icon.svg" color="#1a1a1a"/>
|
|
<link rel="apple-touch-icon" href="/apple-touch-icon.png"/>
|
|
<link rel="stylesheet" href="/main.css"/>
|
|
<link rel="manifest" href="/manifest.webmanifest"/>
|
|
<link rel="license" href="/LICENSE.txt"/>
|
|
<script type="module" src="/js/redirect.js"></script>
|
|
</head>
|
|
<body>
|
|
<header>
|
|
<nav id="site-menu">
|
|
<ul>
|
|
<li><a href="/"><img src="/mask-icon.svg" alt=""/>GrapheneOS</a></li>
|
|
<li><a href="/features">Features</a></li>
|
|
<li><a href="/install/">Install</a></li>
|
|
<li><a href="/build">Build</a></li>
|
|
<li aria-current="page"><a href="/usage">Usage</a></li>
|
|
<li><a href="/faq">FAQ</a></li>
|
|
<li><a href="/releases">Releases</a></li>
|
|
<li><a href="/source">Source</a></li>
|
|
<li><a href="/history/">History</a></li>
|
|
<li><a href="/articles/">Articles</a></li>
|
|
<li><a href="/donate">Donate</a></li>
|
|
<li><a href="/contact">Contact</a></li>
|
|
</ul>
|
|
</nav>
|
|
</header>
|
|
<main id="usage">
|
|
<h1><a href="#usage">Usage guide</a></h1>
|
|
<p>This is a guide covering some aspects of using GrapheneOS. See the
|
|
<a href="/features">features page</a> for a list of GrapheneOS features.</p>
|
|
|
|
<nav id="table-of-contents">
|
|
<h2><a href="#table-of-contents">Table of contents</a></h2>
|
|
<ul>
|
|
<li><a href="#accessibility">Accessibility</a></li>
|
|
<li><a href="#auditor">Auditor</a></li>
|
|
<li>
|
|
<a href="#updates">Updates</a>
|
|
<ul>
|
|
<li><a href="#updates-settings">Settings</a></li>
|
|
<li><a href="#updates-security">Security</a></li>
|
|
<li><a href="#updates-disabling">Disabling</a></li>
|
|
<li><a href="#updates-sideloading">Sideloading</a></li>
|
|
</ul>
|
|
</li>
|
|
<li><a href="#web-browsing">Web browsing</a></li>
|
|
<li><a href="#camera">Camera</a></li>
|
|
<li><a href="#exec-spawning">Exec spawning</a></li>
|
|
<li><a href="#bugs-uncovered-by-security-features">Bugs uncovered by security features</a></li>
|
|
<li>
|
|
<a href="#wifi-privacy">Wi-Fi privacy</a>
|
|
<ul>
|
|
<li><a href="#wifi-privacy-scanning">Scanning</a></li>
|
|
<li><a href="#wifi-privacy-associated">Associated with an Access Point (AP)</a></li>
|
|
</ul>
|
|
</li>
|
|
<li><a href="#lte-only-mode">LTE-only mode</a></li>
|
|
</ul>
|
|
</nav>
|
|
|
|
<section id="accessibility">
|
|
<h2><a href="#accessibility">Accessibility</a></h2>
|
|
|
|
<p>GrapheneOS includes all of the accessibility features from the Android Open
|
|
Source Project and strives to fill in the gaps from not including Google apps and
|
|
services. We include our own fork of the open source TalkBack and Switch Access
|
|
accessibility services along with a Monochromacy option for the standard color
|
|
correction menu.</p>
|
|
|
|
<p>GrapheneOS does not yet include a text-to-speech (TTS) service in the base OS
|
|
due to limitations of the available options. Including one is planned in the
|
|
future when a suitable option is available. RHVoice and eSpeak NG are both open
|
|
source and are the most common choices by GrapheneOS users. Both of these mostly
|
|
work fine but have licensing issues and don't support Direct Boot so they cannot
|
|
be used before the initial unlock of the device. Installing and setting up either
|
|
one of these or another TTS app will get TalkBack working. TalkBack itself
|
|
supports Direct Boot and works before the first unlock but it needs to have a TTS
|
|
app supporting it in order to do more than playing the activation sound before the
|
|
first unlock. After installing a TTS service, you need to select it in the OS
|
|
configuration to accept activating it. The OS will display one of them as already
|
|
selected but it won't simply work from being installed as that wouldn't be safe.
|
|
This is the same as the stock OS but it comes with one set up already.</p>
|
|
|
|
<p>GrapheneOS disables showing the characters as passwords are typed by default.
|
|
You can enable this in Settings ➔ Privacy.</p>
|
|
|
|
<p>Third party accessibility services can be installed and activated. This
|
|
includes the ones made by Google. Most of these will work but some may have a hard
|
|
dependency on functionality from Google Play services for some of their
|
|
functionality or to run at all. Accessibility services are very powerful and we
|
|
strongly recommend against using third party implementations if you can get by
|
|
well without them. We plan to add safeguards in this area while still keeping them
|
|
working without problematic barriers.</p>
|
|
</section>
|
|
|
|
<section id="auditor">
|
|
<h2><a href="#auditor">Auditor</a></h2>
|
|
<p>See the <a href="https://attestation.app/tutorial">tutorial page on the site for the attestation sub-project</a>.</p>
|
|
</section>
|
|
|
|
<section id="updates">
|
|
<h2><a href="#updates">Updates</a></h2>
|
|
|
|
<p>The update system implements automatic background updates. It checks for updates
|
|
approximately once every four hours when there's network connectivity and then
|
|
downloads and installs updates in the background. It will pick up where it left off if
|
|
downloads are interrupted, so you don't need to worry about interrupting it.
|
|
Similarly, interrupting the installation isn't a risk because updates are installed to
|
|
a secondary installation of GrapheneOS which only becomes the active installation
|
|
after the update is complete. Once the update is complete, you'll be informed with a
|
|
notification and simply need to reboot with the button in the notification or via a
|
|
normal reboot. If the new version fails to boot, the OS will be rolled back to the
|
|
past version and the updater will attempt to download and install the update
|
|
again.</p>
|
|
|
|
<p>The updater will use incremental (delta) updates to download only changes rather
|
|
than the whole OS when one is available to go directly from the installed version to
|
|
the latest version. As long as you have working network connectivity on a regular
|
|
basis and reboot when asked, you'll almost always be on one of the past couple
|
|
versions of the OS which will minimize bandwidth usage since incrementals will always
|
|
be available.</p>
|
|
|
|
<p>The updater works while the device is locked / idle, including before the first
|
|
unlock since it's explicitly designed to be able to run before decryption of user
|
|
data.</p>
|
|
|
|
<p>Release changelogs are available <a href="/releases#changelog">in a section on the releases page</a>.</p>
|
|
|
|
<section id="updates-settings">
|
|
<h3><a href="#updates-settings">Settings</a></h3>
|
|
|
|
<p>The settings are available in the Settings app in System ➔ Advanced ➔ Update
|
|
settings.</p>
|
|
|
|
<p>The "Check for updates" option will manually trigger an update check as soon as
|
|
possible. It will still wait for the configuration conditions listed below to be
|
|
satisfied, such as being connected to the internet via one of the permitted network
|
|
types.</p>
|
|
|
|
<p>The "Release channel" setting can be changed from the default Stable channel to the
|
|
Beta channel if you want to help with testing. The Beta channel will usually simply
|
|
follow the Stable channel, but the Beta channel may be used to experiment with new
|
|
features.</p>
|
|
|
|
<p>The "Permitted networks" setting controls which networks will be used to perform
|
|
updates. It defaults to using any network connection. It can be set to "Non-roaming"
|
|
to disable it when the cellular service is marked as roaming or "Unmetered" to disable
|
|
it on cellular networks and also Wi-Fi networks marked as metered.</p>
|
|
|
|
<p>The "Require battery above warning level" setting controls whether updates will
|
|
only be performed when the battery is above the level where the warning message is
|
|
shown. The standard value is at 15% capacity.</p>
|
|
|
|
<p>Enabling the opt-in "Automatic reboot" setting allows the updater to reboot the
|
|
device after an update once it has been idle for a long time. When this setting is
|
|
enabled, a device can take care of any number of updates completely automatically even
|
|
if it's left completely idle.</p>
|
|
</section>
|
|
|
|
<section id="updates-security">
|
|
<h3><a href="#updates-security">Security</a></h3>
|
|
|
|
<p>The update server isn't a trusted party since updates are signed and verified along
|
|
with downgrade attacks being prevented. The update protocol doesn't send identifiable
|
|
information to the update server and works well over a VPN / Tor. GrapheneOS isn't
|
|
able to comply with a government order to build, sign and ship a malicious update to a
|
|
specific user's device based on information like the IMEI, serial number, etc. The
|
|
update server only ends up knowing the IP address used to connect to it and the
|
|
version being upgraded from based on the requested incremental.</p>
|
|
|
|
<p>Android updates can support serialno constraints to make them validate only on a
|
|
certain device but GrapheneOS rejects any update with a serialno constraint for both
|
|
over-the-air updates (Updater app) and sideloaded updates (recovery).</p>
|
|
</section>
|
|
|
|
<section id="updates-disabling">
|
|
<h3><a href="#updates-disabling">Disabling</a></h3>
|
|
|
|
<p>It's highly recommended to leave automatic updates enabled and to configure the
|
|
permitted networks if the bandwidth usage is a problem on your mobile data connection.
|
|
However, it's possible to turn off the update client by going to Settings ➔ Apps,
|
|
enabling Show system via the menu, selecting Seamless Update Client and disabling the
|
|
app. If you do this, you'll need to remember to enable it again to start receiving
|
|
updates.</p>
|
|
</section>
|
|
|
|
<section id="updates-sideloading">
|
|
<h3><a href="#updates-sideloading">Sideloading</a></h3>
|
|
|
|
<p>Updates can be downloaded via
|
|
<a href="https://grapheneos.org/releases">the releases page</a> and installed via recovery
|
|
with adb sideloading. The zip files are signed and verified by recovery, just as they
|
|
are by the update client within the OS. This includes providing downgrade protection,
|
|
which prevents attempting to downgrade the version. If recovery didn't enforce these
|
|
things, they would still be enforced via verified boot including downgrade protection
|
|
and the attempted update would just fail to boot and be rolled back.</p>
|
|
|
|
<p>To install one by sideloading, first, boot into recovery. You may do this either by
|
|
using <code>adb reboot recovery</code> from the operating system, or by selecting the
|
|
"Recovery" option in the bootloader interface.</p>
|
|
|
|
<p>You should see the green Android lying on its back being repaired, with the text "No
|
|
command" meaning that no command has been passed to recovery.</p>
|
|
|
|
<p>Next, access the recovery menu by holding down the power button and pressing the volume
|
|
up button a single time. This key combination toggles between the GUI and text-based mode
|
|
with the menu and log output.</p>
|
|
|
|
<p>Finally, select the "Apply update from ADB" option in the recovery menu and
|
|
sideload the update with adb. For example:</p>
|
|
|
|
<pre>adb sideload blueline-ota_update-2019.07.01.21.zip</pre>
|
|
|
|
<p><strong>You do not need to have adb enabled within the OS or the host's ADB key
|
|
whitelisted within the OS to sideload an update to recovery. Recovery mode does not
|
|
trust the attached computer and this can be considered a production feature. Trusting
|
|
a computer with ADB access within the OS is much different and exposes the device to a
|
|
huge amount of attack surface and control by the trusted computer.</strong></p>
|
|
</section>
|
|
</section>
|
|
|
|
<section id="usb-peripherals">
|
|
<h2><a href="#usb-peripherals">USB peripherals</a></h2>
|
|
|
|
<p>GrapheneOS defaults to ignoring connected USB peripherals when the device is
|
|
already booted and the screen is locked. A USB device already connected at boot
|
|
will still work. The purpose is reducing attack surface for a locked device with
|
|
active login sessions to user profiles to protect data that's not at rest. This
|
|
can be controlled in Settings ➔ Security ➔ USB accessories. The options are:</p>
|
|
|
|
<ul>
|
|
<li>Disallow new USB peripherals</li>
|
|
<li>Allow new USB peripherals when unlocked (default)</li>
|
|
<li>Allow new USB peripherals (like stock Android)</li>
|
|
</ul>
|
|
|
|
<p>This option has no impact on the device acting as a USB peripheral itself when
|
|
connected to a computer. Android defaults to charge only mode and requires opt-in
|
|
to the device being used for file transfer, USB tethering, MIDI or PTP.</p>
|
|
</section>
|
|
|
|
<section id="web-browsing">
|
|
<h2><a href="#web-browsing">Web browsing</a></h2>
|
|
|
|
<p>GrapheneOS includes a Vanadium subproject providing privacy and security enhanced
|
|
releases of Chromium. Vanadium is both the user-facing browser included in the OS and
|
|
the provider of the WebView used by other apps to render web content. The WebView is
|
|
the browser engine used by the vast majority of web browsers and nearly all other apps
|
|
embedding web content or using web technologies for other uses.</p>
|
|
|
|
<p>Using Vanadium is highly recommended. Bromite is a solid alternative and is the
|
|
only other browser we recommend. Bromite provides integrated ad-blocking and more
|
|
advanced anti-fingerprinting. For now, Vanadium is more focused on security hardening
|
|
and Bromite is more focused on anti-fingerprinting. The projects are collaborating
|
|
together and will likely converge to providing more of the same features. Vanadium
|
|
will be providing content filtering and anti-fingerprinting, but it needs to be done
|
|
in a way that meets the standards of the project, which takes time.</p>
|
|
|
|
<p>Vanadium is designed for use on GrapheneOS and does not duplicate the OS privacy
|
|
and security features such as the hardened malloc implementation. This leads to some
|
|
of the differences from Bromite, such as relying on OS support for encrypted DNS
|
|
rather than enabling Chromium's DNS-over-HTTPS support.</p>
|
|
|
|
<p>Chromium-based browsers like Vanadium and Bromite provide the strongest sandbox
|
|
implementation, leagues ahead of the alternatives. It is much harder to escape from
|
|
the sandbox and it provides much more than acting as a barrier to compromising the
|
|
rest of the OS. Site isolation enforces security boundaries around each site using the
|
|
sandbox by placing each site into an isolated sandbox. It required a huge overhaul of
|
|
the browser since it has to enforce these rules on all the IPC APIs. Site isolation is
|
|
important even without a compromise, due to side channels. Browsers without site
|
|
isolation are very vulnerable to attacks like Spectre. On mobile, due to the lack of
|
|
memory available to apps, there are different modes for site isolation. Vanadium turns
|
|
on strict site isolation, matching Chromium on the desktop. Bromite enables strict
|
|
site isolation on high memory devices, including all the devices that are officially
|
|
supported by GrapheneOS.</p>
|
|
|
|
<p>Chromium has decent exploit mitigations, unlike the available alternatives. This is
|
|
improved upon in Vanadium by enabling further mitigations, including those developed
|
|
upstream but not yet fully enabled due to code size, memory usage or performance. For
|
|
example, it enables type-based CFI like Chromium on the desktop, uses a stronger SSP
|
|
configuration, zero initializes variables by default, etc. Some of the mitigations are
|
|
inherited from the OS itself, which also applies to other browsers, at least if they
|
|
don't do things to break them.</p>
|
|
|
|
<p>We recommend against trying to achieve browser privacy and security through piling
|
|
on browser extensions and modifications. Most privacy features for browsers are
|
|
privacy theater without a clear threat model and these features often reduce privacy
|
|
by aiding fingerprinting and adding more state shared between sites. Every change you
|
|
make results in you standing out from the crowd and generally provides more ways to
|
|
track you. Enumerating badness via content filtering is not a viable approach to
|
|
achieving decent privacy, just as AntiVirus isn't a viable way to achieving decent
|
|
security. These are losing battles, and are at best a stopgap reducing exposure while
|
|
waiting for real privacy and security features.</p>
|
|
|
|
<p>Vanadium will be following the school of thought where hiding the IP address
|
|
through Tor or a trusted VPN shared between many users is the essential baseline, with
|
|
the browser partitioning state based on site and mitigating fingerprinting to avoid
|
|
that being trivially bypassed. The Tor Browser's approach is the only one with any
|
|
real potential, however flawed the current implementation may be. This work is
|
|
currently in a very early stage and it is largely being implemented upstream with the
|
|
strongest available implementation of state partitioning. Chromium is using Network
|
|
Isolation Keys to divide up connection pools, caches and other state based on site and
|
|
this will be the foundation for privacy. Chromium itself aims to prevent tracking
|
|
through mechanisms other than cookies, greatly narrowing the scope downstream work
|
|
needs to cover. Bromite is doing a lot of work in these areas and Vanadium will be
|
|
benefiting from that along with this upstream work. The focus is currently on research
|
|
since we don't see much benefit in deploying bits and pieces of this before everything
|
|
is ready to come together. At the moment, the only browser with any semblance of
|
|
privacy is the Tor Browser but there are many ways to bypass the anti-fingerprinting
|
|
and state partitioning. The Tor Browser's security is weak which makes the privacy
|
|
protection weak. The need to avoid diversity (fingerprinting) creates a monoculture
|
|
for the most interesting targets. This needs to change, especially since Tor itself
|
|
makes people into much more of a target (both locally and by the exit nodes).</p>
|
|
|
|
<p>WebView-based browsers use the hardened Vanadium rendering engine, but they can't
|
|
offer as much privacy and control due to being limited to the capabilities supported
|
|
by the WebView widget. For example, they can't provide a setting for toggling sensors
|
|
access because the feature is fairly new and the WebView WebSettings API doesn't yet
|
|
include support for it as it does for JavaScript, location, cookies, DOM storage and
|
|
other older features. For sensors, the Sensors app permission added by GrapheneOS can
|
|
be toggled off for the browser app as a whole instead. The WebView sandbox also
|
|
currently runs every instance within the same sandbox and doesn't support site
|
|
isolation.</p>
|
|
|
|
<p>Avoid Gecko-based browsers like Firefox as they're currently much more vulnerable
|
|
to exploitation and inherently add a huge amount of attack surface. Gecko doesn't have
|
|
a WebView implementation (GeckoView is not a WebView implementation), so it has to be
|
|
used alongside the Chromium-based WebView rather than instead of Chromium, which means
|
|
having the remote attack surface of two separate browser engines instead of only one.
|
|
Firefox / Gecko also bypass or cripple a fair bit of the upstream and GrapheneOS
|
|
hardening work for apps. Worst of all, Firefox runs as a single process on mobile and
|
|
has no sandbox beyond the OS sandbox. This is despite the fact that Chromium semantic
|
|
sandbox layer on Android is implemented via the OS <code>isolatedProcess</code>
|
|
feature, which is a very easy to use boolean property for app service processes to
|
|
provide strong isolation with only the ability to communicate with the app running
|
|
them via the standard service API. Even in the desktop version, Firefox's sandbox is
|
|
still substantially weaker (especially on Linux, where it can hardly be considered a
|
|
sandbox at all) and lacks support for isolating sites from each other rather than only
|
|
containing content as a whole.</p>
|
|
</section>
|
|
|
|
<section id="camera">
|
|
<h2><a href="#camera">Camera</a></h2>
|
|
|
|
<p>The Camera app included in GrapheneOS is very basic and can't take full advantage
|
|
of the hardware. It doesn't offer much in the way of configuration. In the long term,
|
|
it's going to be replaced. In the short term, there are other apps available providing
|
|
more capabilities and better support for taking advantage of the hardware.</p>
|
|
|
|
<p>The Pixel 3 (but not the Pixel 3a) and Pixel 4 (but not the Pixel 4a) have a
|
|
Pixel Visual Core / Pixel Neural Core providing a hardware-based implementation of
|
|
HDR+. HDR+ captures many images and intelligently merges data across them, taking
|
|
into account motion, etc. It substantially improves the quality of images,
|
|
especially in low light. This is used transparently for third party apps that are
|
|
compatible with it, and there isn't an explicit switch to turn it on or off for
|
|
most of them. An example of a compatible app is Open Camera's default
|
|
configuration, or Open Camera with the Camera 2 API and other settings (including
|
|
the the various knobs / toggles outside of the settings menu) left alone. In
|
|
general, HDR+ will work transparently in most apps as long as they keep things
|
|
simple and use a good minimalist approach to taking pictures. It should work
|
|
transparently in most messaging apps, etc. with internal support for taking
|
|
pictures.</p>
|
|
|
|
<p>In addition to supporting HDR+ via the Pixel Visual Core, or similar features on
|
|
other devices with the same constraints, Open Camera offers advanced configuration and
|
|
various advanced features. Make sure to enable the Camera 2 API in the settings, which
|
|
should be the default, but the app doesn't have a great user interface / user
|
|
experience. You probably don't want to use the traditional HDR feature in the app.
|
|
That's not HDR+, but rather captures 3 images and merges them in a way that isn't at
|
|
all intelligent and causes a lot of blur and distortion. The HDR+ implementation can
|
|
actually benefit from the camera not being completely steady as it's smart enough to
|
|
match up the picture and it provides it with more data vs. a traditional HDR
|
|
implementation where it essentially doesn't work without a tripod and is not really at
|
|
all useful on a phone unless you actually have that for it.</p>
|
|
</section>
|
|
|
|
<section id="exec-spawning">
|
|
<h2><a href="#exec-spawning">Exec spawning</a></h2>
|
|
|
|
<p>GrapheneOS creates fresh processes (via exec) when spawning applications instead of
|
|
using the traditional Zygote spawning model. This improves privacy and security at the
|
|
expense of higher cold start app spawning time and higher initial memory usage. It
|
|
doesn't impact runtime performance beyond the initial spawning time. It adds somewhere
|
|
in the ballpark of 100ms to app spawning time on the flagship devices and is only very
|
|
noticeable on lower-end devices with a weaker CPU and slower storage. The spawning
|
|
time impact only applies when the app doesn't already have an app process and the OS
|
|
will try to keep app processes cached in the background until memory pressure forces
|
|
it to start killing them.</p>
|
|
|
|
<p>In the typical Zygote model, a template app process is created during boot and
|
|
every app is spawned as a clone of it. This results in every app sharing the same
|
|
initial memory content and layout, including sharing secrets that are meant to be
|
|
randomized for each process. It saves time by reusing the initialization work. The
|
|
initial memory usage is reduced due to copy-on-write semantics resulting in memory
|
|
written only during initialization being shared between app processes.</p>
|
|
|
|
<p>The Zygote model weakens the security provided by features based on random secrets
|
|
including Address Space Layout Randomization (ASLR), stack canaries, heap canaries,
|
|
randomized heap layout and memory tags. It cripples these security features since
|
|
every app has the values for every other app and the values don't change for fresh app
|
|
processes until reboot. Much of the OS itself is implemented via non-user-facing apps
|
|
with privileges reserved for OS components. The Zygote template is reused across user
|
|
profiles, so it also provides a temporary set of device identifiers across profiles
|
|
for each boot via the shared randomized values.</p>
|
|
</section>
|
|
|
|
<section id="bugs-uncovered-by-security-features">
|
|
<h2><a href="#bugs-uncovered-by-security-features">Bugs uncovered by security features</a></h2>
|
|
|
|
<p>GrapheneOS substantially expands the standard mitigations for memory corruption
|
|
vulnerabilities. Some of these features are designed to directly catch the memory
|
|
corruption bugs either via an explicit check or memory protection and abort the
|
|
program in order to prevent them from being exploited. Other features mitigate issues
|
|
a bit less directly such as zeroing data immediately upon free, isolated memory
|
|
regions, heap randomization, etc. and can also lead to latent memory corruption bugs
|
|
crashing instead of the program continuing onwards with corrupted memory. This means
|
|
that many latent memory corruption bugs in apps are caught along with some in the OS
|
|
itself. These bugs are not caused by GrapheneOS, but rather already existed and are
|
|
uncovered by the features. The features are aimed at preventing or hindering exploits,
|
|
not finding bugs, but they do that as part of doing their actual job.</p>
|
|
|
|
<p>Similarly, some of the other privacy and security improvements reduce the access
|
|
available to applications and they may crash. Some of these features are always
|
|
enabled under the hood, while others like the Network and Sensors toggles are
|
|
controlled by users via opt-in or opt-out toggles. Apps may not handle having access
|
|
taken away like this, although it generally doesn't cause any issues as it's all
|
|
designed to be friendly to apps and fully compatible rather than killing the
|
|
application when it violates the rules.</p>
|
|
|
|
<p>If you run into an application aborting, try to come up with a process for
|
|
reproducing the issue and then capture a bug report via the 'Take bug report' feature
|
|
in Developer options. Report an issue to the GrapheneOS OS issue tracker and email the
|
|
bug report capture zip to contact@grapheneos.org with the issue tracker number in the
|
|
subject like "Bug report capture for issue #104". The bug report capture includes
|
|
plain text 'tombstones' with logs, tracebacks, address space layout, register content
|
|
and a tiny bit of context from memory from areas that are interesting for debugging.
|
|
This may contain some sensitive data. Feel free to provide only the tombstone for the
|
|
relevant crash and filter out information you don't want to send. However, it will be
|
|
more difficult to debug if you provide less of the information. If the app doesn't
|
|
work with sensitive information, just send the whole tombstone.</p>
|
|
</section>
|
|
|
|
<section id="wifi-privacy">
|
|
<h2><a href="#wifi-privacy">Wi-Fi privacy</a></h2>
|
|
|
|
<p>Wi-Fi on GrapheneOS is very privacy-friendly and is essentially anonymous as long
|
|
as apps do not leak uniquely identifying information to the network. GrapheneOS avoids
|
|
allowing itself to be fingerprinted as GrapheneOS, other than connections which are
|
|
documented (see the FAQ) and can be easily disabled or forced through a VPN
|
|
service.</p>
|
|
|
|
<section id="wifi-privacy-scanning">
|
|
<h3><a href="#wifi-privacy-scanning">Scanning</a></h3>
|
|
|
|
<p>MAC randomization is always performed for Wi-Fi scanning. Pixel
|
|
phones have firmware support for scanning MAC randomization going
|
|
<a href="https://android-developers.googleblog.com/2017/04/changes-to-device-identifiers-in.html">significantly beyond a naive implementation</a>.
|
|
On many other devices, there are identifiers exposed by Wi-Fi scanning beyond the MAC
|
|
address such as the packet sequence number and assorted identifying information in the
|
|
probe requests.</p>
|
|
|
|
<p>Avoid using hidden APs (i.e. APs not broadcasting their SSID) since all
|
|
known hidden SSIDs end up being broadcast as part of scanning for networks to
|
|
find them again. SSIDs are not broadcast for standard non-hidden APs. Hidden
|
|
APs are only hidden when no devices are connected. It makes little sense as a
|
|
privacy feature, especially for a non-mobile AP where knowing the AP exists
|
|
can't be used for tracking it since it doesn't move. The feature reduces your
|
|
privacy rather than increasing it. If you need to use a hidden AP, make sure
|
|
to delete the saved network afterwards.</p>
|
|
|
|
<p>Wi-Fi and Bluetooth scanning for improving location detection are disabled by
|
|
default, unlike the stock OS. These can be toggled in Settings ➔ Location ➔ Wi-Fi and
|
|
Bluetooth scanning. These features enable scanning even when Wi-Fi or Bluetooth is
|
|
disabled, so these need to be kept disabled to fully disable the radios when Wi-Fi and
|
|
Bluetooth are disabled. GrapheneOS doesn't yet have an implementation of a coarse
|
|
location service to supplement GPS location, so enabling these options doesn't
|
|
actually do anything at the moment. Implementing a supplementary location service is
|
|
planned but we need a robust, secure and private implementation via a local database.
|
|
The initial focus will likely be a cell phone tower database, so these features still
|
|
wouldn't be relevant.</p>
|
|
</section>
|
|
|
|
<section id="wifi-privacy-associated">
|
|
<h3><a href="#wifi-privacy-associated">Associated with an Access Point (AP)</a></h3>
|
|
|
|
<p>The DHCP client uses the anonymity profile rather than sending a hostname so it
|
|
doesn't compromise the privacy offered by MAC randomization.</p>
|
|
|
|
<p>Associated MAC randomization is performed by default. This can be controlled
|
|
per-network with Settings ➔ Network & Internet ➔ Wi-Fi ➔ <network> ➔
|
|
Advanced ➔ Privacy.</p>
|
|
|
|
<p>In the stock OS, the default is to use a unique persistent random MAC address for
|
|
each network. It has 2 options available: "Use randomized MAC (default)" and "Use
|
|
device MAC". In GrapheneOS, the default is generating a new random MAC address when
|
|
connecting to a network. It has 3 options available: "Use fully randomized MAC
|
|
(default)", "Use per-network randomized MAC" and "Use device MAC".</p>
|
|
|
|
<p>GrapheneOS also disables support for stable link-local IPv6 addresses, since these
|
|
have the potential to be used as identifiers. It's more sensible to use typical
|
|
link-local address generation based on the (randomized) MAC address since link-local
|
|
devices have access to both. As of Android 11, Android only uses stable link-local
|
|
privacy addresses when MAC randomization is disabled, so we no longer need to disable
|
|
the feature.</p>
|
|
</section>
|
|
</section>
|
|
|
|
<section id="lte-only-mode">
|
|
<h2><a href="#lte-only-mode">LTE-only mode</a></h2>
|
|
|
|
<p>If you have a reliable LTE connection from your carrier, you can reduce attack
|
|
surface by disabling 2G / 3G connectivity in Settings ➔ Network & Internet ➔
|
|
Mobile network ➔ Preferred network type. Traditional voice calls will only work in
|
|
the LTE-only mode if you have either an LTE connection and VoLTE (Voice over LTE)
|
|
support or a Wi-Fi connection and VoWi-Fi (Voice over Wi-Fi) support. VoLTE /
|
|
VoWi-Fi works on GrapheneOS for most carriers unless they restrict it to carrier
|
|
phones. US carriers other than T-Mobile tend to be missing these features due to
|
|
us not including their proprietary apps.</p>
|
|
|
|
<p>This feature is not intended to improve the confidentiality of traditional calls and
|
|
texts, but it might somewhat raise the bar for some forms of interception. It's not a
|
|
substitute for end-to-end encrypted calls / texts or even transport layer encryption.
|
|
LTE does provide basic network authentication / encryption, but it's for the network
|
|
itself. The intention of the LTE-only feature is only hardening against remote
|
|
exploitation by disabling an enormous amount of legacy code.</p>
|
|
</section>
|
|
</main>
|
|
<footer>
|
|
<a href="/"><img src="/mask-icon.svg" width="512" height="512" alt=""/>GrapheneOS</a>
|
|
<ul id="social">
|
|
<li><a href="https://twitter.com/GrapheneOS">Twitter</a></li>
|
|
<li><a href="https://github.com/GrapheneOS">GitHub</a></li>
|
|
<li><a href="https://reddit.com/r/GrapheneOS">Reddit</a></li>
|
|
<li><a href="https://www.linkedin.com/company/grapheneos/">LinkedIn</a></li>
|
|
</ul>
|
|
</footer>
|
|
</body>
|
|
</html>
|