rewrote quickstart, build-process

[AGL/documentation.git] / docs / 2_Architecture_Guides / 2.2_Security_Blueprint / 5_Platform / 1.2.5.2_SystemD.md

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+---
+edit_link: ''
+title: SystemD
+origin_url: >-
+  https://raw.githubusercontent.com/automotive-grade-linux/docs-sources/master/docs/security-blueprint/part-5/2-SystemD.md
+---
+
+<!-- WARNING: This file is generated by fetch_docs.js using /home/boron/Documents/AGL/docs-webtemplate/site/_data/tocs/architecture/master/security_blueprint-security-blueprint-book.yml -->
+
+# SystemD
+
+`afm-system-daemon` is used to:
+
+- Manage users and user sessions.
+- Setup applications and services (_CGroups_, _namespaces_, autostart, permissions).
+- Use of `libsystemd` for its programs (event management, **D-Bus** interface).
+
+<!-- section-config -->
+
+Domain             | Object         | Recommendations
+------------------ | -------------- | ------------------------------------
+Platform-SystemD-1 | Security model | Use Namespaces for containerization.
+Platform-SystemD-2 | Security model | Use CGroups to organise processes.
+
+<!-- end-section-config -->
+
+See [systemd integration and user management](http://iot.bzh/download/public/2017/AMM-Dresden/AGL-systemd.pdf) for more information.
+
+## Benefits
+
+- Removal of one privileged process: **afm-user-daemon**
+- Access and use of high level features:
+
+  - Socket activation.
+  - Management of users and integration of **PAM**.
+  - Dependency resolution to services.
+  - `Cgroups` and resource control.
+  - `Namespaces` containerization.
+  - Autostart of required API.
+  - Permissions and security settings.
+  - Network management.
+
+<!-- pagebreak -->
+
+## CGroups
+
+Control Groups offer a lot of features, with the most useful ones you can
+control: Memory usage, how much CPU time is allocated, how much device I/O is
+allowed or which devices can be accessed. **SystemD** uses _CGroups_ to organise
+processes (each service is a _CGroups_, and all processes started by that
+service use that _CGroups_). By default, **SystemD** automatically creates a
+hierarchy of slice, scope and service units to provide a unified structure for
+the _CGroups_ tree. With the `systemctl` command, you can further modify this
+structure by creating custom slices. Currently, in AGL, there are 2 slices
+(**user.slice** and **system.slice**).
+
+## Namespaces
+
+### User side
+
+There are several ways of authenticating users (Key Radio Frequency, Phone,
+Gesture, ...). Each authentication provides dynamic allocation of **uids** to
+authenticated users. **Uids** is used to ensure privacy of users and **SMACK**
+for applications privacy.
+
+First, the user initiates authentication with **PAM** activation. **PAM**
+Standard offers highly configurable authentication with modular design like
+face recognition, Voice identification or with a password. Then users should
+access identity services with services and applications.