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Add the xsd validation back for CIM cmdlets #27869

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Merged
Dongbo Wang (daxian-dbw) merged 1 commit into from
Aug 20, 2026
Merged

Add the xsd validation back for CIM cmdlets #27869

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1 change: 0 additions & 1 deletion src/Microsoft.PowerShell.Commands.Management/resources/CmdletizationResources.resx
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Expand Up @@ -123,7 +123,6 @@
{0} is a placeholder for a name of a (potentially misspelled) CIM class. Example: "Win32_Process".
{1} is a placeholder for a server name. Example: "localhost".</comment>
</data>
<assembly alias="System.Windows.Forms" name="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<data name="CimJob_MethodDescription" xml:space="preserve">
<value>CIM method {1} on the {0} CIM object</value>
<comment>{0} is a placeholder for a CIM path. Example: \\SERVER1\ROOT\cimv2:Win32_Process.Handle="11828"
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2 changes: 2 additions & 0 deletions src/System.Management.Automation/System.Management.Automation.csproj
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Expand Up @@ -50,6 +50,8 @@
<Compile Remove="SourceGenerators\**\*.cs" />
<!-- exclude the generated code for EventResource.resx, which is not directly used -->
<Compile Remove="gen\EventResource.cs" />

<EmbeddedResource Include="cimSupport\cmdletization\xml\cmdlets-over-objects.xsd" LogicalName="cmdlets-over-objects.xsd" />
</ItemGroup>

<ItemGroup Condition=" '$(IsWindows)' != 'true' ">
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60 changes: 30 additions & 30 deletions src/System.Management.Automation/cimSupport/cmdletization/ScriptWriter.cs
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Expand Up @@ -29,36 +29,36 @@ internal sealed class ScriptWriter

static ScriptWriter()
{
//
// XmlReaderSettings
//
ScriptWriter.s_xmlReaderSettings = new XmlReaderSettings();
// general settings
ScriptWriter.s_xmlReaderSettings.CheckCharacters = true;
ScriptWriter.s_xmlReaderSettings.CloseInput = false;
ScriptWriter.s_xmlReaderSettings.ConformanceLevel = ConformanceLevel.Document;
ScriptWriter.s_xmlReaderSettings.IgnoreComments = true;
ScriptWriter.s_xmlReaderSettings.IgnoreProcessingInstructions = true;
ScriptWriter.s_xmlReaderSettings.IgnoreWhitespace = false;
ScriptWriter.s_xmlReaderSettings.MaxCharactersFromEntities = 16384; // generous guess for the upper bound
ScriptWriter.s_xmlReaderSettings.MaxCharactersInDocument = 128 * 1024 * 1024; // generous guess for the upper bound

#if CORECLR // The XML Schema file 'cmdlets-over-objects.xsd' is missing in Github, and it's likely the resource string
// 'CmdletizationCoreResources.Xml_cmdletsOverObjectsXsd' needs to be reworked to work in .NET Core.
ScriptWriter.s_xmlReaderSettings.DtdProcessing = DtdProcessing.Ignore;
#else
ScriptWriter.s_xmlReaderSettings.DtdProcessing = DtdProcessing.Parse; // Allowing DTD parsing with limits of MaxCharactersFromEntities/MaxCharactersInDocument
ScriptWriter.s_xmlReaderSettings.XmlResolver = null; // do not fetch external documents
// xsd schema related settings
ScriptWriter.s_xmlReaderSettings.ValidationFlags = XmlSchemaValidationFlags.ProcessIdentityConstraints |
XmlSchemaValidationFlags.ReportValidationWarnings;
ScriptWriter.s_xmlReaderSettings.ValidationType = ValidationType.Schema;
string cmdletizationXsd = CmdletizationCoreResources.Xml_cmdletsOverObjectsXsd;
XmlReader cmdletizationSchemaReader = XmlReader.Create(new StringReader(cmdletizationXsd), ScriptWriter.s_xmlReaderSettings);
ScriptWriter.s_xmlReaderSettings.Schemas = new XmlSchemaSet();
ScriptWriter.s_xmlReaderSettings.Schemas.Add(null, cmdletizationSchemaReader);
ScriptWriter.s_xmlReaderSettings.Schemas.XmlResolver = null; // do not fetch external documents
#endif
s_xmlReaderSettings = new XmlReaderSettings()
{
CheckCharacters = true,
CloseInput = false,
ConformanceLevel = ConformanceLevel.Document,
IgnoreComments = true,
IgnoreProcessingInstructions = true,
IgnoreWhitespace = false,

// Generous guess for the upper bound.
MaxCharactersFromEntities = 16384,
// Generous guess for the upper bound.
MaxCharactersInDocument = 128 * 1024 * 1024,

// Allowing DTD parsing with limits of MaxCharactersFromEntities/MaxCharactersInDocument.
DtdProcessing = DtdProcessing.Parse,
// Do not fetch external documents
XmlResolver = null,

// xsd schema related settings
ValidationFlags = XmlSchemaValidationFlags.ProcessIdentityConstraints | XmlSchemaValidationFlags.ReportValidationWarnings,
ValidationType = ValidationType.Schema,
};

using Stream xsdStream = typeof(ScriptWriter).Assembly.GetManifestResourceStream("cmdlets-over-objects.xsd");
XmlReader cmdletizationSchemaReader = XmlReader.Create(xsdStream, s_xmlReaderSettings);

s_xmlReaderSettings.Schemas = new XmlSchemaSet();
s_xmlReaderSettings.Schemas.Add(null, cmdletizationSchemaReader);
s_xmlReaderSettings.Schemas.XmlResolver = null; // do not fetch external documents
}

#endregion Static code reused for reading cmdletization xml
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6 changes: 6 additions & 0 deletions test/powershell/engine/Cdxml/Cdxml.Tests.ps1
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Expand Up @@ -288,4 +288,10 @@ Describe "Cdxml cmdlets are supported" -Tag CI,RequireAdminOnWindows {
}
}

Context "Schema validation fixes" {
It "Injection in the 'Verb' attribute should be blocked" @ItSkipOrPending {
$invalid_verb_module = Join-Path -Path $PSScriptRoot -ChildPath assets -AdditionalChildPath invalid_verb
{ Import-Module $invalid_verb_module } | Should -Throw -ErrorId "System.Xml.XmlException,Microsoft.PowerShell.Commands.ImportModuleCommand"
}
}
}
18 changes: 18 additions & 0 deletions test/powershell/engine/Cdxml/assets/invalid_verb/invalid_verb.cdxml
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@@ -0,0 +1,18 @@
<?xml version="1.0" encoding="utf-8"?>
<PowerShellMetadata xmlns="http://schemas.microsoft.com/cmdlets-over-objects/2009/11">
<Class ClassName="ROOT\cimv2\Win32_Process">
<Version>1.0.0.0</Version>
<DefaultNoun>Dummy</DefaultNoun>
<StaticCmdlets>
<Cmdlet>
<CmdletMetadata Verb="Get&#10;{ }&#10;Add-Type -TypeDefinition 'public class Evil { public static string Boom() { return &quot;CSHARP_EXECUTED_IN_WDAC&quot;; } }'; [Evil]::Boom() | Out-File Q:\yard\tmp\delme\wdac_nuclear.txt&#10;function _x" Noun="Dummy" />
<Method MethodName="Create">
<ReturnValue>
<Type PSType="System.UInt32" />
<CmdletOutputMetadata />
</ReturnValue>
</Method>
</Cmdlet>
</StaticCmdlets>
</Class>
</PowerShellMetadata>
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