diff options
| author | Daniel Micay <daniel.micay@grapheneos.org> | 2024-06-21 13:50:40 -0400 |
|---|---|---|
| committer | Daniel Micay <daniel.micay@grapheneos.org> | 2024-06-21 16:05:46 -0400 |
| commit | f25155f056ca0476157cfa37e1cb7ffe9d11277f (patch) | |
| tree | 9e5b77258ad6b10ca7a7e5cc717ec90511b94e5c /static/features.html | |
| parent | 7cb01fc3bd97323f6ed77403d9a511a53a24fdc7 (diff) | |
overhaul explanation of USB-C port control
Diffstat (limited to 'static/features.html')
| -rw-r--r-- | static/features.html | 42 |
1 files changed, 29 insertions, 13 deletions
diff --git a/static/features.html b/static/features.html index 7955d807..ea4888f9 100644 --- a/static/features.html +++ b/static/features.html @@ -28,6 +28,7 @@ <link rel="manifest" href="/manifest.webmanifest"/> <link rel="license" href="/LICENSE.txt"/> <link rel="me" href="https://grapheneos.social/@GrapheneOS"/> + [[js|/js/redirect.js]] </head> <body> {% with current_page="features" %} @@ -81,7 +82,7 @@ <li><a href="#attack-surface-reduction">Attack surface reduction</a> <ul> - <li><a href="#usb-c-port-control">USB-C port control</a></li> + <li><a href="#usb-c-port-and-pogo-pins-control">USB-C port and pogo pins control</a></li> </ul> </li> <li><a href="#exploit-mitigations">Exploit @@ -254,16 +255,14 @@ settings screen.</li> </ul> - <h5 id="usb-c-port-control"><a href="#usb-c-port-control">USB-C port control</a></h5> + <h5 id="usb-c-port-and-pogo-pins-control"><a href="#usb-c-port-and-pogo-pins-control">USB-C port and pogo pins control</a></h5> - <p>Our USB-C port mode setting for Tensor Pixels offers precise control over - USB functions, allowing complete disabling of USB controller functionality - including data lines.</p> - - <p>Unlike the standard Android USB HAL and device administration API, our - USB-C port control fully disables USB-C functionality at the hardware level - using device-specific kernel modifications. This greatly reduces the USB-C - attack surface based on the chosen setting.</p> + <p>Our <b>USB-C port and pogo pins</b> setting protects against attacks + through USB-C or pogo pins while the OS is booted. For the majority of + devices without pogo pins, the setting is labelled <b>USB-C port</b>. We + have a less advanced version of this feature on devices launched prior to + October 2021 (Pixel 5a and earlier) since it requires a hardware-specific + implementation with driver changes.</p> <p>The feature has five modes:</p> @@ -276,9 +275,26 @@ </ul> <p>The default is <b>Charging-only when locked</b>, which significantly - reduces attack surface when the device is locked. After locking, new - connections are blocked immediately, and data lines are disabled when - existing connections end.</p> + reduces attack surface when the device is locked. After locking, it blocks + any new USB connections immediately through either USB-C and pogo pins at + both the hardware level via configuring the USB controller and also at the + OS level in the kernel to provide a second layer of defense. It disables the + data lines at a hardware level as soon as the existing connections end which + happens right away if there were new USB connections. It also disables USB-C + alternate modes including DisplayPort at both the OS and hardware level.</p> + + <p>Our implementation is far more secure than Android's standard USB HAL + toggle available to device admin apps. The standard feature only disables + high level USB handling in the OS. It doesn't block new USB connections or + disable the data lines at a hardware level. It also leaves the handling of + the USB-C and pogo pins protocols enabled in the OS, and it doesn't deal + with USB-C alternate modes. The standard feature is also either blocking or + not blocking USB at a high level, without the ability to block new + connections and disable USB only once the existing connections end. Other + operating systems trying to implement a similar feature via the standard + toggle end up continuing to allow new USB connections in the OS until all + connections end instead of the 2 phase approach we use for our two + Charging-only when locked modes.</p> </section> <section id="exploit-mitigations"> |