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diff --git a/doc/application-framework.html b/doc/application-framework.html new file mode 100644 index 0000000..f77ee48 --- /dev/null +++ b/doc/application-framework.html @@ -0,0 +1,290 @@ +<html> +<head> + <link rel="stylesheet" type="text/css" href="doc.css"> + <meta charset="UTF-8"> +</head> +<body> +<a name="Application.framework"></a> +<h1>Application framework</h1> + +<pre><code>version: 1 +Date: 14 March 2016 +Author: José Bollo +</code></pre> + +<a name="Foreword"></a> +<h2>Foreword</h2> + +<p>This document describes what we intend to do. It may happen that our +current implementation and the content of this document differ.</p> + +<p>In case of differences, it is assumed that this document is right +and the implementation is wrong.</p> + +<a name="Introduction"></a> +<h2>Introduction</h2> + +<p>During the first works in having the security model of Tizen +integrated in AGL (Automotive Grade Linux) distribution, it became +quickly obvious that the count of components specific to Tizen +to integrate was huge.</p> + +<p>Here is a minimal list of what was needed:</p> + +<ul> +<li>platform/appfw/app-installers</li> +<li>platform/core/security/cert-svc</li> +<li>platform/core/appfw/ail</li> +<li>platform/core/appfw/aul-1</li> +<li>platform/core/appfw/libslp-db-util</li> +<li>platform/core/appfw/pkgmgr-info</li> +<li>platform/core/appfw/slp-pkgmgr</li> +</ul> + + +<p>But this list is complete because many dependencies are hidden. +Those hidden dependencies are including some common libraries but also many +tizen specific sub-components (iniparser, bundle, dlog, libtzplatform-config, +db-util, vconf-buxton, …).</p> + +<p>This is an issue because AGL is not expected to be Tizen. Taking it would +either need to patch it for removing unwanted components or to take all +of them.</p> + +<p>However, a careful study of the core components of the security framework +of Tizen showed that their dependencies to Tizen are light (and since some +of our work, there is no more dependency to tizen). +Those components are <strong>cynara</strong>, <strong>security-manager</strong>, <strong>D-Bus aware of cynara</strong>.</p> + +<p>Luckyly, these core security components of Tizen are provided +by <a href="https://github.com/01org/meta-intel-iot-security" title="A collection of layers providing security technologies">meta-intel-iot-security</a>, a set of yocto layers. +These layers were created by Intel to isolate Tizen specific security +components from the initial port of Tizen to Yocto. +The 3 layers are providing components for:</p> + +<ul> +<li>Implementing Smack LSM</li> +<li>Implementing Integrity Measurement Architecture</li> +<li>Implementing Tizen Security Framework</li> +</ul> + + +<p>The figure below shows the history of these layers.</p> + +<pre><code> 2014 2015 +Tizen OBS ----------+---------------------------> + \ + \ + Tizen Yocto +---------+--------------> + \ + \ + meta-intel-iot-security +-----------> +</code></pre> + +<p>We took the decision to use these security layers that provides the +basis of the Tizen security, the security framework.</p> + +<p>For the components of the application framework, built top of +the security framework, instead of pulling the huge set of packages +from Tizen, we decided to refit it by developping a tiny set of +components that would implement the same behaviour but without all +the dependencies and with minor architectural improvements for AGL.</p> + +<p>These components are <strong>afm-system-daemon</strong> and <strong>afm-user-daemon</strong>. +They provides infrastructure for installing, uninstalling, +launching, terminating, stopping and resuming applications in +a multi user secure environment.</p> + +<p>A third component exists in the framework, the binder <strong>afb-daemon</strong>. +The binder provides the easiest way to provide secured API for +any tier. Currently, the use of the binder is not absolutely mandatory.</p> + +<p>This documentation explains the framework created by IoT.bzh +by rewriting the Tizen Application Framework. Be aware of the +previous foreword.</p> + +<a name="Overview"></a> +<h2>Overview</h2> + +<p>The figure below shows the major components of the framework +and their interactions going through the following scenario: +APPLICATION installs an other application and then launch it.</p> + +<pre><code>+-----------------------------------------------------------------------+ +| User | +| ................................ | +| : Smack isolation context : | +| : : ........................... | +| : +-----------------------+ : : Smack isolation context : | +| : | | : : : | +| : | APPLICATION | : : OTHER application : | +| : | | : :.........................: | +| : +-----------+-----------+ : ^ | +| : | : | | +| : |(1),(7) : |(13) | +| : | : | | +| : +-----------v-----------+ : +---------+---------------+ | +| : | binder afb-daemon | : | | | +| : +-----------------------+ : | afm-user-daemon | | +| : | afm-main-plugin | : | | | +| : +-----+--------------+--+ : +------^-------+------+---+ | +| :........|..............|......: | | : | +| |(2) |(8) |(10) | : | +| | | | | : | +| | +----v--------------------+---+ | : | +| | | D-Bus session | |(11) :(12) | +| | +-------------------------+---+ | : | +| | | | : | +| | |(9) | : | +| | | | : | +:===========|===================================|=======|======:========: +| | | | : | +| | +---v-------v--+ : | +| +------v-------------+ (3) | | : | +| | D-Bus system +-----------------> CYNARA | : | +| +------+-------------+ | | : | +| | +------^-------+ : | +| |(4) | : | +| | |(6) v | +| +------v--------------+ +---------+---------------+ | +| | | (5) | | | +| | afm-system-daemon +-------------> SECURITY-MANAGER | | +| | | | | | +| +---------------------+ +-------------------------+ | +| | +| System | ++-----------------------------------------------------------------------+ +</code></pre> + +<p>Let follow the sequence of calls:</p> + +<ol> +<li><p>APPLICATION calls its <strong>binder</strong> to install the OTHER application.</p></li> +<li><p>The plugin <strong>afm-main-plugin</strong> of the <strong>binder</strong> calls, through +<strong>D-Bus</strong> system, the system daemon to install the OTHER application.</p></li> +<li><p>The system <strong>D-Bus</strong> checks wether APPLICATION has the permission +or not to install applications by calling <strong>CYNARA</strong>.</p></li> +<li><p>The system <strong>D-Bus</strong> transmits the request to <strong>afm-system-daemon</strong>.</p> + +<p><strong>afm-system-daemon</strong> checks the application to install, its +signatures and rights and install it.</p></li> +<li><p><strong>afm-system-daemon</strong> calls <strong>SECURITY-MANAGER</strong> for fullfilling +security context of the installed application.</p></li> +<li><p><strong>SECURITY-MANAGER</strong> calls <strong>CYNARA</strong> to install initial permissions +for the application.</p></li> +<li><p>APPLICATION call its binder to start the nearly installed OTHER application.</p></li> +<li><p>The plugin <strong>afm-main-plugin</strong> of the <strong>binder</strong> calls, through +<strong>D-Bus</strong> session, the user daemon to launch the OTHER application.</p></li> +<li><p>The session <strong>D-Bus</strong> checks wether APPLICATION has the permission +or not to start an application by calling <strong>CYNARA</strong>.</p></li> +<li><p>The session <strong>D-Bus</strong> transmits the request to <strong>afm-user-daemon</strong>.</p></li> +<li><p><strong>afm-user-daemon</strong> checks wether APPLICATION has the permission +or not to start the OTHER application <strong>CYNARA</strong>.</p></li> +<li><p><strong>afm-user-daemon</strong> uses <strong>SECURITY-MANAGER</strong> features to set +the seciruty context for the OTHER application.</p></li> +<li><p><strong>afm-user-daemon</strong> launches the OTHER application.</p></li> +</ol> + + +<p>This scenario does not cover all the features of the frameworks. +Shortly because details will be revealed in the next chapters, +the components are:</p> + +<ul> +<li><p><strong><em>SECURITY-MANAGER</em></strong>: in charge of setting Smack contexts and rules, +of setting groups, and, of creating initial content of <em>CYNARA</em> rules +for applications.</p></li> +<li><p><strong><em>CYNARA</em></strong>: in charge of handling API access permissions by users and by +applications.</p></li> +<li><p><strong><em>D-Bus</em></strong>: in charge of checking security of messaging. The usual D-Bus +security rules are enhanced by <em>CYNARA</em> checking rules.</p></li> +<li><p><strong><em>afm-system-daemon</em></strong>: in charge of installing and uninstalling applications.</p></li> +<li><p><strong><em>afm-user-daemon</em></strong>: in charge of listing applications, querying application details, +starting, terminating, stopping, resuming applications and their instances +for a given user context.</p></li> +<li><p><strong><em>afb-binder</em></strong>: in charge of serving resources and features through an +HTTP interface.</p></li> +<li><p><strong><em>afm-main-plugin</em></strong>: This plugin allows applications to use the API +of the AGL framework.</p></li> +</ul> + + +<a name="Links.between.the..Security.framework..and.the..Application.framework."></a> +<h2>Links between the “Security framework” and the “Application framework”</h2> + +<p>The security framework refers to the security model used to ensure +security and to the tools that are provided for implementing that model.</p> + +<p>The security model refers to how DAC (Discretionnary Access Control), +MAC (Mandatory Access Control) and Capabilities are used by the system +to ensure security and privacy. It also includes features of reporting +using audit features and by managing logs and alerts.</p> + +<p>The application framework manages the applications: +installing, uninstalling, starting, stopping, listing …</p> + +<p>The application framework uses the security model/framework +to ensure the security and the privacy of the applications that +it manages.</p> + +<p>The application framework must be compliant with the underlyiong +security model/framework. But it should hide it to the applications.</p> + +<a name="The.security.framework"></a> +<h2>The security framework</h2> + +<p>The implemented security model is the security model of Tizen 3. +This model is described <a href="https://wiki.tizen.org/wiki/Security/Tizen_3.X_Overview" title="Tizen 3 security overview">here</a>.</p> + +<p>The security framework then comes from Tizen 3 but through +the <a href="https://github.com/01org/meta-intel-iot-security" title="A collection of layers providing security technologies">meta-intel</a>. +It includes: <strong>Security-Manager</strong>, <strong>Cynara</strong> +and <strong>D-Bus</strong> compliant to Cynara.</p> + +<p>Two patches are applied to the security-manager. These patches are removing +dependencies to packages specific of Tizen but that are not needed by AGL. +None of these patches adds or removes any behaviour.</p> + +<p><strong>Theoritically, the security framework/model is an implementation details +that should not impact the layers above the application framework</strong>.</p> + +<p>The security framework of Tizen provides “nice lad” a valuable component to +scan log files and analyse auditing. This component is still in developement.</p> + +<a name="The.application.framework"></a> +<h2>The application framework</h2> + +<p>The application framework on top of the security framework +provides the components to install and uninstall applications +and to run it in a secured environment.</p> + +<p>The goal is to manage applications and to hide the details of +the security framework to the applications.</p> + +<p>For the reasons explained in introduction, we did not used the +application framework of Tizen as is but used an adaptation of it.</p> + +<p>The basis is kept identical: the applications are distributed +in a digitally signed container that must match the specifications +of widgets (web applications). This is described by the technical +recomendations <a href="http://www.w3.org/TR/widgets" title="Packaged Web Apps">widgets</a> and <a href="http://www.w3.org/TR/widgets-digsig" title="XML Digital Signatures for Widgets">widgets-digsig</a> of the W3 consortium.</p> + +<p>This model allows the distribution of HTML, QML and binary applications.</p> + +<p>The management of signatures of the widget packages +This basis is not meant as being rigid and it can be extended in the +futur to include for example incremental delivery.</p> + +<a name="Comparison.to.other.frameworks"></a> +<h2>Comparison to other frameworks</h2> + +<a name="Tizen.framework"></a> +<h3>Tizen framework</h3> + +<a name="xdg-app"></a> +<h3>xdg-app</h3> + +<a name="ostro"></a> +<h3>ostro</h3> +</body> +</html> |