Re: security/strong name/zones clarification needed

From: Peter Singer (petes@knorrassociates.com)
Date: 02/03/03 

From: "Peter Singer" <petes@knorrassociates.com>
Date: Mon, 3 Feb 2003 06:25:28 -0800

Shawn,

I'm still missing something. I've got a simple user
control with one button on it. There's only one method,
namely New(), in the entire app. I've got the following
code in there:

  Dim zz As New System.Security.PermissionSet
(System.Security.Permissions.PermissionState.None)
  Dim KAIpk As Byte() = {the csv byte string}
  Dim KAIpkblob As New
System.Security.Permissions.StrongNamePublicKeyBlob(KAIpk)
  Dim xx As New
System.Security.Permissions.StrongNameIdentityPermission
(KAIpkblob, Nothing, Nothing)
  zz.AddPermission(xx)
  zz.Assert()

It still doesn't let me see the control in IE. What am I
missing?

Thanks,
Peter

>-----Original Message-----
>The Assert needs to go in the method of your control that
is at the top of
>the callstack. So, everywhere that code flow enters your
control, those
>methods should get the asserts.
>
>--
>This posting is provided "AS IS" with no warranties, and
confers no rights.
>Please do not send email directly to this alias, this
alias is for newsgroup
>purposes only.
>
>
>"Peter Singer" <petes@knorrassociates.com> wrote in
message
>news:06dc01c2c963$40d177d0$89f82ecf@TK2MSFTNGXA01...
>> Shawn,
>>
>> Thanks. I'm a bit confused. So I've got my dll that's
>> embedded in an OBJECT tag. Does the Assert code go in
its
>> constructor?
>>
>> I'm not clear on what the code needs to look like. I
tried:
>>
>> Dim zz As New System.Security.PermissionSet
>> (System.Security.Permissions.PermissionState.None)
>>
>> Dim KAIpk As Byte() = {a bunch of csv numbers}
>> Dim KAIpkblob As New
>> System.Security.Permissions.StrongNamePublicKeyBlob
(KAIpk)
>> Dim xx As New
>> System.Security.Permissions.StrongNameIdentityPermission
>> (KAIpkblob, Nothing, Nothing)
>>
>> zz.AddPermission(xx)
>> zz.Assert()
>>
>> And I've tried:
>>
>> Dim zz As New System.Security.PermissionSet
>>
(System.Security.Permissions.PermissionState.Unrestricted)
>> zz.Assert()
>>
>> neither of which worked. Can you clarify please?
>>
>> Peter
>>
>>
>> >-----Original Message-----
>> >Hi Peter,
>> >
>> > You're running into an interesting scenario.
>> When assemblies are
>> >executed in a web page, they are hosted by IE. When IE
>> realizes it
>> >needs to host the CLR, it creates an AppDomain, but due
>> to the fact that
>> >this AppDomain needs to be setup before your assembly
can
>> be loaded, only
>> >minimal evidence can be supplied to it. So in this
>> instance, only the fact
>> >that it is on the Internet zone and its URL can be
>> supplied. Any evidence
>> >specific to the assembly being loaded, such as the
>> publisher's certificate
>> >or a strong name cannot be given to the assembly, as it
>> is not loaded yet.
>> > Once the AppDomain is setup, the assembly is loaded
>> into it. At this
>> >point, the CLR sees all the evidence that applies to
the
>> assembly, but it is
>> >too late to apply this evidence to the AppDomain. So
>> your assembly itself
>> >will recieve the permission grant you expect (in this
>> case, FullTrust). So
>> >far, so good.
>> > Now your assembly is executing with the FullTrust
>> permission set. But
>> >it is going to make an API call. A permission check is
>> now started.
>> >Your assembly will have enough permissions, but the
code
>> access security
>> >engine works with a call-stack walk, meaning that every
>> method and AppDomain
>> >on the current call stack must have enough permission
to
>> call the requested
>> >API. When the call stack is initiated, it hits the
>> AppDomain boundary
>> >within the IE host that did not get given your strong
>> name signature as
>> >evidence. This means that this AppDomain boundary will
>> only resolve to
>> >Internet permissions. And so the SecurityException is
>> thrown.
>> > The work around for this is simple. Stack walks
can
>> be prevented by
>> >asserting permissions. Any time a stack walk
encounters
>> a stack frame where
>> >a set of permissions have been asserted, the walk
returns
>> successfully,
>> >without proceeding any further. So the easiest thing
to
>> do would be to
>> >create a permission set in your entry point methods
that
>> consists of all the
>> >permissions you need, and call the .Assert() method of
>> that permission set.
>> >
>> >-Shawn
>> >--
>> >This posting is provided "AS IS" with no warranties,
and
>> confers no rights.
>> >Please do not send email directly to this alias, this
>> alias is for newsgroup
>> >purposes only.
>> >
>> >
>> >"Peter Singer" <petes@knorrassociates.com> wrote in
>> message
>> >news:06df01c2c7b9$5b8d9dc0$8df82ecf@TK2MSFTNGXA02...
>> >> I have a win app that I've posted on an intranet web
>> >> server. All my assemblies are strong named. I've
went in
>> >> to the .net security configuration tool and granted
>> >> anything with my strong name full trust. All other
>> >> settings (including intranet) are at their defaults.
>> >>
>> >> I can do http://localhost/myapp.exe and it works
fine.
>> >> However, if I access an html page that has an
assembly
>> >> embedded in an object tag I never get the control to
>> >> display (I get the little square w/a square, circle
and
>> >> triangle in it). If I grant the Intranet zone full
trust
>> >> though, it works.
>> >>
>> >> I thought doing a http://localhost/myapp.exe runs the
>> app
>> >> inside of the IEEXEC context, which takes on the
>> security
>> >> as if running w/in IE. If that's the case why is
>> >> http://localhost/myapp.exe working but
>> >> http://localhost/myapp.html (with the embedded object
>> tag)
>> >> not (unless I grant full trust to Intranet)?
>> >>
>> >
>> >
>> >.
>> >
>
>
>.
>