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diff --git a/doc/application-framework.md b/doc/application-framework.md index 35ad960..ac6d40d 100644 --- a/doc/application-framework.md +++ b/doc/application-framework.md @@ -3,7 +3,7 @@ Application framework ===================== version: 1 - Date: 14 March 2016 + Date: 15 March 2016 Author: José Bollo Foreword @@ -16,278 +16,103 @@ In case of differences, it is assumed that this document is right and the implementation is wrong. -Introduction ------------- - -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. - -Here is a minimal list of what was needed: - - - platform/appfw/app-installers - - platform/core/security/cert-svc - - platform/core/appfw/ail - - platform/core/appfw/aul-1 - - platform/core/appfw/libslp-db-util - - platform/core/appfw/pkgmgr-info - - platform/core/appfw/slp-pkgmgr - -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, ...). - -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. - -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 **cynara**, **security-manager**, **D-Bus aware of cynara**. - -Luckyly, these core security components of Tizen are provided -by [meta-intel-iot-security][meta-intel], 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: - - * Implementing Smack LSM - * Implementing Integrity Measurement Architecture - * Implementing Tizen Security Framework - -The figure below shows the history of these layers. - - - 2014 2015 - Tizen OBS ----------+---------------------------> - \ - \ - Tizen Yocto +---------+--------------> - \ - \ - meta-intel-iot-security +-----------> - -We took the decision to use these security layers that provides the -basis of the Tizen security, the security framework. - -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. - -These components are **afm-system-daemon** and **afm-user-daemon**. -They provides infrastructure for installing, uninstalling, -launching, terminating, stopping and resuming applications in -a multi user secure environment. - -A third component exists in the framework, the binder **afb-daemon**. -The binder provides the easiest way to provide secured API for -any tier. Currently, the use of the binder is not absolutely mandatory. - -This documentation explains the framework created by IoT.bzh -by rewriting the Tizen Application Framework. Be aware of the -previous foreword. - - Overview -------- -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. - - +-----------------------------------------------------------------------+ - | 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 | - +-----------------------------------------------------------------------+ - -Let follow the sequence of calls: - -1. APPLICATION calls its **binder** to install the OTHER application. - -2. The plugin **afm-main-plugin** of the **binder** calls, through - **D-Bus** system, the system daemon to install the OTHER application. - -3. The system **D-Bus** checks wether APPLICATION has the permission - or not to install applications by calling **CYNARA**. - -4. The system **D-Bus** transmits the request to **afm-system-daemon**. - - **afm-system-daemon** checks the application to install, its - signatures and rights and install it. - -5. **afm-system-daemon** calls **SECURITY-MANAGER** for fullfilling - security context of the installed application. - -6. **SECURITY-MANAGER** calls **CYNARA** to install initial permissions - for the application. - -7. APPLICATION call its binder to start the nearly installed OTHER application. - -8. The plugin **afm-main-plugin** of the **binder** calls, through - **D-Bus** session, the user daemon to launch the OTHER application. - -9. The session **D-Bus** checks wether APPLICATION has the permission - or not to start an application by calling **CYNARA**. - -10. The session **D-Bus** transmits the request to **afm-user-daemon**. - -11. **afm-user-daemon** checks wether APPLICATION has the permission - or not to start the OTHER application **CYNARA**. - -12. **afm-user-daemon** uses **SECURITY-MANAGER** features to set - the seciruty context for the OTHER application. - -13. **afm-user-daemon** launches the OTHER application. - -This scenario does not cover all the features of the frameworks. -Shortly because details will be revealed in the next chapters, -the components are: - -* ***SECURITY-MANAGER***: in charge of setting Smack contexts and rules, - of setting groups, and, of creating initial content of *CYNARA* rules - for applications. - -* ***CYNARA***: in charge of handling API access permissions by users and by - applications. - -* ***D-Bus***: in charge of checking security of messaging. The usual D-Bus - security rules are enhanced by *CYNARA* checking rules. +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. -* ***afm-system-daemon***: in charge of installing and uninstalling applications. +The goal is to manage applications and to hide the details of +the security framework to the applications. -* ***afm-user-daemon***: in charge of listing applications, querying application details, - starting, terminating, stopping, resuming applications and their instances - for a given user context. +For the reasons explained in introduction, we did not used the +application framework of Tizen as is but used an adaptation of it. -* ***afb-binder***: in charge of serving resources and features through an - HTTP interface. +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 [widgets] and [widgets-digsig] of the W3 consortium. -* ***afm-main-plugin***: This plugin allows applications to use the API - of the AGL framework. +This model allows the distribution of HTML, QML and binary applications. +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. -Links between the "Security framework" and the "Application framework" ----------------------------------------------------------------------- -The security framework refers to the security model used to ensure -security and to the tools that are provided for implementing that model. +Comparison to other frameworks +------------------------------ -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. +### Tizen framework -The application framework manages the applications: -installing, uninstalling, starting, stopping, listing ... +### xdg-app -The application framework uses the security model/framework -to ensure the security and the privacy of the applications that -it manages. +### ostro -The application framework must be compliant with the underlyiong -security model/framework. But it should hide it to the applications. +Organisation of directory of applications +========================================= +The main path for applivcations are: APPDIR/PKGID/VER. -The security framework ----------------------- +Where: -The implemented security model is the security model of Tizen 3. -This model is described [here][tizen-secu-3]. + - APPDIR is as defined above + - PKGID is a directory whose name is the package identifier + - VER is the version of the package MAJOR.MINOR -The security framework then comes from Tizen 3 but through -the [meta-intel]. -It includes: **Security-Manager**, **Cynara** -and **D-Bus** compliant to Cynara. +This organisation has the advantage to allow several versions to leave together. +This is needed for some good reasons (rolling back) and also for less good reasons (user habits). -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. +Identity of installed files +--------------------------- -**Theoritically, the security framework/model is an implementation details -that should not impact the layers above the application framework**. +All the files are installed as the user "userapp" and group "userapp". +All files have rw(x) for user and r-(x) for group and others. -The security framework of Tizen provides "nice lad" a valuable component to -scan log files and analyse auditing. This component is still in developement. +This allows any user to read the files. -The application framework -------------------------- +Labelling the directories of applications +----------------------------------------- -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. -The goal is to manage applications and to hide the details of -the security framework to the applications. +Organisation of data +==================== -For the reasons explained in introduction, we did not used the -application framework of Tizen as is but used an adaptation of it. +The data of a user are in its directory and are labelled using the labels of the application -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 [widgets] and [widgets-digsig] of the W3 consortium. +Setting Smack rules for the application +======================================= -This model allows the distribution of HTML, QML and binary applications. +For Tizen, the following rules are set by the security manager for each application. -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. + System ~APP~ rwx + System ~PKG~ rwxat + System ~PKG~::RO rwxat + ~APP~ System wx + ~APP~ System::Shared rxl + ~APP~ System::Run rwxat + ~APP~ System::Log rwxa + ~APP~ _ l + User ~APP~ rwx + User ~PKG~ rwxat + User ~PKG~::RO rwxat + ~APP~ User wx + ~APP~ User::Home rxl + ~APP~ User::App::Shared rwxat + ~APP~ ~PKG~ rwxat + ~APP~ ~PKG~::RO rxl +Here, ~PKG~ is the identifier of the package and ~APP~ is the identifier of the application. -Comparison to other frameworks ------------------------------- +What user can run an application? +================================= -### Tizen framework +Not all user are able to run all applications. +How to manage that? -### xdg-app -### ostro |