ba67727687
This CL is part of the Chrome OS source code directory migration: https://docs.google.com/document/d/1g-98HpzA8XcoGBWUv1gQNr4rbnD5yfvbtYZyPDDbkaE. Change-Id: Ic8ba8bf79d84fc92f34a126f38e930386900d57f Bug: 1164001 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2960289 Commit-Queue: Yeunjoo Choi <ychoi@igalia.com> Reviewed-by: Hidehiko Abe <hidehiko@chromium.org> Owners-Override: Hidehiko Abe <hidehiko@chromium.org> Cr-Commit-Position: refs/heads/master@{#892453}
51 lines
2.6 KiB
Markdown
51 lines
2.6 KiB
Markdown
# D-Bus Mojo Connection Service
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## Overview
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D-Bus Mojo Connection Service in Chrome is a D-Bus service that helps to
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bootstrap CrOS services' Mojo connection.
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## Bootstrap a new CrOS service
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D-Bus Mojo Connection Service lives in [//chrome/browser/ash/dbus/mojo_connection_service_provider.h](https://chromium.googlesource.com/chromium/src.git/+/main/chrome/browser/ash/dbus/mojo_connection_service_provider.h).
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Follow the example of CrOS Sensors' [changelist](https://chromium-review.googlesource.com/c/chromium/src/+/2352298).
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### Steps to Add a usage for a CrOS process with a new D-Bus method:
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1. Add a method name in both CrOS platform and Chrome.
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(Recommend: `platform2/system_api`)
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2. Add the busconfig policy in [MojoConnectionService.conf].
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3. Upon a D-Bus request coming from the CrOS service, pass one endpoint of the
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generated Mojo pipe to the component in Chrome that needs a Mojo channel to
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the CrOS service. Ex: [RegisterServer](https://chromium-review.googlesource.com/c/chromium/src/+/2352298/16/chrome/browser/ash/dbus/mojo_connection_service_provider.cc#74) in CrOS Sensors' usage.
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4. Respond to the D-Bus request with the other endpoint of the generated Mojo
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pipe. (Recommend: use the helper function [SendResponse](https://chromium-review.googlesource.com/c/chromium/src/+/2352298/16/chrome/browser/ash/dbus/mojo_connection_service_provider.h#75))
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The Mojo pipe can also be generated in the CrOS process, and pass the endpoint
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of it as the D-Bus argument to the service provider, instead of allowing Chrome
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to generate the pipe.
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### Steps to Add a usage for a CrOS process with an existing D-Bus method:
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1. Add the busconfig policy in [MojoConnectionService.conf].
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And that’s it. The method name and the logic in the service provider can be
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reused.
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## Security
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UID filtering should be used to ensure only the needed processes are calling
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the specific D-Bus methods, as processes/applications calling D-Bus APIs are
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trusted (written and reviewed by Chromium/CrOS teams) and should have a
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well-known UID to be filtered.
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UID filtering: Define access permission for each UID in
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[MojoConnectionService.conf]. Only the processes run under the specific UIDs can
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send respective D-Bus requests to the service provider.
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Arguments/tokens in D-Bus methods are still available if needed, which should
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be enough for multi-login situations and handling failures. The arguments can
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also be used to determine if Chromium should accept the request, and which Mojo
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interface should be used to establish the Mojo channel.
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[MojoConnectionService.conf]: https://chromium.googlesource.com/chromium/src.git/+/main/chrome/browser/ash/dbus/org.chromium.MojoConnectionService.conf
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