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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-A4179FF3-4541-44B8-A8F3-52C1318159B3" xml:lang="en"><title>Platform

    13 Security</title><shortdesc>This document discusses how device drivers should implement platform

    14 security.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    15 <p>Device drivers must follow the Symbian platform security guidelines. As

    16 a part of platform security, drivers must be given the necessary platform

    17 security capabilities. A driver can also check the capabilities of a process

    18 opening a channel on the device, in order to restrict access to the device. </p>

    19 <section id="GUID-74BFFE9A-2904-4EFC-952A-581844A9095B"><p><b>Driver-side

    20 definition</b> </p> <p>Because drivers are loaded by the Kernel, both LDDs

    21 and PDDs must have the same level of trust and capability as the Kernel. This

    22 means that platform security capabilities must be set to <codeph>ALL</codeph> in

    23 the LDD and PDD <filepath>.mmp</filepath> files. </p> <codeblock id="GUID-91D17A93-4DFE-58DB-A071-F82399B7D9CE" xml:space="preserve">// LDD: mmp file

    24 ...

    25 CAPABILITY     ALL</codeblock> <codeblock id="GUID-68471C34-7E9A-5CE7-BED3-1F3C6AEB08BF" xml:space="preserve">// PDD: mmp file

    26 ...

    27 CAPABILITY     ALL</codeblock> <p>The user program must have the necessary

    28 capability set in its <filepath>.mmp</filepath> file to open and access the

    29 driver API. The reference documentation for the API should say what capabilities

    30 are required. Usually, they are the same as the minimum capability that is

    31 required to load the drivers. </p> <codeblock id="GUID-18BF036F-1A2E-59AA-BF8E-05D80B7916B5" xml:space="preserve">// Test application: mmp file

    32 ...

    33 CAPABILITY    CommDD ReadDeviceData PowerMgmt</codeblock></section>

    34 <section id="GUID-7177D7FD-088C-432F-BABC-4E5DAA0E07D4"><p><b>User-side verification</b> </p> <p>A

    35 device driver must check the capability of the process that is accessing it.

    36 This is typically done during channel creation and, if required, for specific

    37 requests to the LDD. The Kernel provides the <xref href="GUID-C6946ECB-775F-3EC2-A56F-78F25B9FBE3D.dita#GUID-C6946ECB-775F-3EC2-A56F-78F25B9FBE3D/GUID-E34E27F2-921A-3F78-9DE3-C5B16F37CF8B"><apiname>Kern::CurrentThreadHasCapability()</apiname></xref> API

    38 to check the capability of the calling process. It can check for more than

    39 one capability. </p> <p>The following shows how the example driver checks

    40 during channel creation that the user has the <xref href="GUID-460F2258-02FB-316E-8044-4649E4488486.dita"><apiname>ECapabilityCommD</apiname></xref> capability: </p> <codeblock id="GUID-79B4EB40-14C8-5BDA-9FC9-A82DF87C83A7" xml:space="preserve">TInt DExDriverLogicalChannel::DoCreate(TInt /*aUnit*/, const TDesC8* 

    41 /*anInfo*/, const TVersion& aVer)

    42     {

    43     // Capability check - CommDD

    44     if (!Kern::CurrentThreadHasCapability (ECapabilityCommDD,

    45     __PLATSEC_DIAGNOSTIC_STRING("Checked by Tutorial Driver")))

    46         return KErrPermissionDenied;    

    47     ...

    48     }</codeblock></section>

    49 <section id="GUID-7B302793-1A00-40D6-8E9A-BA694541D0D4"><p><b>Data caging </b> </p> <p>Symbian

    50 platform security requires that all DLLs and EXEs are placed in the folder <filepath>/sys/bin</filepath>.

    51 Drivers and test application binaries must be placed in the <filepath>/sys/bin</filepath> folder

    52 by their ROM <filepath>.iby</filepath> file. </p> <codeblock id="GUID-42FE3528-37BB-5DD2-B565-4DB527EBC596" xml:space="preserve">// iby file

    53 device[VARID]=KERNEL_DIR\DEBUG_DIR\exdriver_ldd.ldd     \Sys\Bin\exdriver_ldd.ldd

    54 device[VARID]=KERNEL_DIR\DEBUG_DIR\exdriver_pdd.pdd     \Sys\Bin\exdriver_pdd.pdd

    55 file=ABI_DIR\BUILD_DIR\exdriver_test.exe                \Sys\Bin\exdriver_test.exe

    56 </codeblock></section>

    57 </conbody><related-links>

    58 <link href="GUID-EA20E614-C911-4EE9-92B5-C8F9B657D59E.dita"><linktext>Platform

    59 security architecture</linktext></link>

    60 </related-links></concept>