SSRS - Custom Code - ssrs-2008

Question

I'm trying to access a REST service from a function written in the custom code of a report. I don't want to move that code into a separate assembly so the problem is around the custom code, please don't send me to custom assemblies.
Here's the code:
Public Shared Function GetData(ByVal id As String) As String
Dim strURL As String = ("http://..." & id)
Dim webRequest As System.Net.HttpWebRequest = DirectCast(System.Net.WebRequest.Create(strURL), System.Net.HttpWebRequest)
webRequest.Method = "Get"
Dim webResponse As System.Net.HttpWebResponse = DirectCast(webRequest.GetResponse, System.Net.HttpWebResponse)
Dim rdr As New System.IO.StreamReader(webResponse.GetResponseStream)
Return rdr.ReadToEnd
End Function
When I'm using it i receive the error:
System.Security.SecurityException: Request for the permission of type 'System.Net.WebPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.
at System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet)
at System.Security.CodeAccessPermission.Demand()
at System.Net.HttpWebRequest..ctor(Uri uri, ServicePoint servicePoint)
at System.Net.HttpRequestCreator.Create(Uri Uri)
at System.Net.WebRequest.Create(Uri requestUri, Boolean useUriBase)
at System.Net.WebRequest.Create(String requestUriString)
at ReportExprHostImpl.CustomCodeProxy.GetData(String what, String id, String defaultValue)
The action that failed was:
Demand
The type of the first permission that failed was:
System.Net.WebPermission
The Zone of the assembly that failed was:
MyComputer
And I suppose that I may have future problems with System.IO too.
I had a look on CAS and I'm totally blurred, I don't know what policy file I have to change, what code group I have to change and how.
My understanding is that this is the code group used for custom code (in rssrvpolicy.config):
<CodeGroup
class="UnionCodeGroup"
version="1"
PermissionSetName="Execute"
Name="Report_Expressions_Default_Permissions"
Description="This code group grants default permissions for code in report expressions and Code element.>
<IMembershipCondition
class="StrongNameMembershipCondition"
version="1"
PublicKeyBlob="002400...CAEDDA2"
/>
</CodeGroup>
but simply setting the PermissionSetName to Fulltrust doesn't make any change.

Answer 1

For anyone experiencing this issue (a year and a half after the fact), if you are receiving this exception when trying to view the report from BIDS, then you need to update the RSPreviewPolicy.config file in your Visual Studio's PrivateAssemblies directory.
There are three security policy files that need to be modified for uses like this (custom code in expression or custom assemblies.) Detailed notes (including a seriously crucial one on where to place new CodeGroup elements!!) can be found on the MSDN page titled (as of today) "Using Reporting Services Security Policy Files". The security config files are the report server config (rssrvpolicy.config), the report manager config (rsmgrpolicy.config) and the report designer config (RSPreviewPolicy.config).
A great test for this is to update one at a time and test all three after each update (after deploying a report to your report server instance of course : ).

Answer 2

You should try PermissionSetName="FULLTRUST" in the codegroup.