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<!DOCTYPE concept+
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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">+
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<concept id="GUID-9E4D75C0-D797-5541-8E52-3C6D154CC74A" xml:lang="en"><title>ECom+
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and the Platform Security Architecture</title><prolog><metadata><keywords/></metadata></prolog><conbody>+
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<p>The Symbian Platform Security Architecture is designed to provide defences+
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against malicious or badly implemented code. The following aspects of platform+
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security are particularly relevant to the ECom plug-in architecture: </p>+
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<ul>+
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<li id="GUID-299B3BF1-9A55-5CCC-AA77-49F4EBE07ABD"><p>The <i>platform security+
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capability model</i>, which protects processes from loading and using DLLs+
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that are less secure than the process itself. </p> </li>+
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<li id="GUID-92E6F90B-EFE0-5026-AA61-1C068376C21C"><p>Control over software+
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installation, so that insecure software cannot disrupt legitimately installed+
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software. </p> </li>+
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<li id="GUID-2DE8CE05-57EE-582F-80F8-BAEB82B38FAB"><p>Control over which processes+
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have access to particular files. </p> </li>+
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</ul>+
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<p>For more information on the Platform Security Architecture, see <i>Symbian+
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OS v9 Security Architecture</i> in the <xref href="GUID-9E4D75C0-D797-5541-8E52-3C6D154CC74A.dita">Platform+
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security</xref> section. </p>+
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<section><title>ECom and the platform security capability model</title> <p>The+
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Platform Security Architecture protects processes against loading and using+
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DLLs that are less secure than the processes themselves. This is done using+
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platform security capabilities assigned to the process and the DLL. The rule+
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applied is that the DLL must have the same or greater capabilities than the+
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process in which it is loaded. </p> <p>With ECom, a plug-in is a DLL that+
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is loaded into a client process when an interface implementation provided+
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by that DLL is instantiated. If the plug-in DLL has lower capabilities than+
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the loading process, then a "permission denied" (-46) error is returned. See <xref href="GUID-8A7B837D-4069-5364-A596-686EEBAE351D.dita">How to troubleshoot plug-in+
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loading errors</xref> for details of how to investigate this error. </p> <p>Providers+
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of plug-in DLLs must consider the following with respect to platform security+
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capabilities: </p> <ul>+
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<li id="GUID-FB693866-59D7-56DD-9FF4-07AB3CDDA9F7"><p>If you give a plug-in+
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DLL no capabilities, it can only be used by client processes that also have+
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no capabilities. </p> </li>+
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<li id="GUID-8FA6F9BF-9631-5110-8121-219041C07C4A"><p>If you intend a plug-in+
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to work only with one client program, such as a particular server, then the+
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documentation for that program should tell you what capabilities it needs. </p> </li>+
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<li id="GUID-494937B7-AF39-5222-A97E-5F7478A4EC9E"><p>If you want a plug-in+
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to be usable by any program (apart from the kernel and the file server), then+
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the capability setting <codeph>All -Tcb</codeph> may be what you require.+
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Note, however, programs with such high platform security capabilities require+
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signing and authorisation to be installed by users on phones. See <xref href="https://www.symbiansigned.com/" scope="external">Symbian Signed</xref> for details. </p> </li>+
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<li id="GUID-B5CD618B-F202-553A-BB5F-F1DF9AF70B58"><p> <i> Custom resolver</i> plug-ins+
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are a special case. They are loaded by a server process in ECom itself, and+
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so must be trusted by that server. This requires that you give the plug-in+
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the <codeph>ProtServ</codeph> capability. See <xref href="GUID-E10A3336-9C4C-59A5-B94F-6CECA92FFB9F.dita">How+
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to provide a custom resolver</xref> for more details on writing resolvers. </p> </li>+
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</ul> <p>Platform security also allows you to specify that clients should+
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only use plug-in implementations supplied by a particular company. See <xref href="GUID-7F4692A0-1801-5D91-8F28-06075AC45DE2.dita">How to filter implementations+
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by vendor ID</xref> for more details. </p> </section>+
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<section><title>Installation and upgrade controls</title> <p>Under Platform+
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Security, the Software Installer program controls what software is installed+
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to the device. It enables programs originally delivered in ROM, including+
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ECom plugins, to be upgraded securely. </p> <p>Before platform security, applications+
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could chose to use only ROM-based plug-ins. This guaranteed that the plug-ins+
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were secure, but did not allow upgrades. Alternatively, both ROM-based and+
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installed plug-ins were used, which allowed upgrades, but also risked the+
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use of possibly insecure plug-ins. </p> <p>Platform security improves this+
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situation, as it allows clients to access securely both ROM-based plug-ins+
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and any installed upgrades to those plug-ins. For more information for how+
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clients can do this, see <xref href="GUID-08007041-CE18-5B1C-9AE6-042EBBFD1AB6.dita">Using+
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the ROM-only resolver</xref>. </p> <p>Providers of ROM-based plug-ins should+
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see <xref href="GUID-93F53961-9DA3-5D01-A881-D28E0EBF8B3C.dita">How to upgrade+
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ROM-based plug-ins securely</xref>. </p> </section>+
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<section><title>File locations</title><p>The Platform Security architecture+
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tightly controls access to executable code by: <ul>+
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<li><p>requiring that all such code, including plug-in DLLs, is located under+
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a directory <filepath>\sys\bin</filepath></p></li>+
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<li><p>restricting access to that directory to a small number of key system+
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processes. </p></li>+
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</ul></p><p>The registration resource file for a plug-in must be readable+
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by ECom, but should not be alterable after installation. For this reason,+
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registration resource files are always installed to the read-only directory <filepath>\resource\plugins</filepath>.</p><p>To+
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build plug-in code to these locations, set the target type in the project+
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file to <codeph>PLUGIN</codeph>. For more information, see the <xref href="GUID-641A276D-F618-50CE-BA5A-658DCC26BAB5.dita">Creating an Implementation+
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Project File</xref> section.  </p> </section>+
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</conbody></concept>+
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