Cross-Database Impersonation Fail for Service Account

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                          I would like to enable an application that dumps a big ol' heap of data into a Staging area to be able to kickoff the stored procedure that transforms & loads the data into the Production area. If possible, I'd like to **not** grant the application any access to the production area.  Unfortunately, [EXECUTE AS](https://learn.microsoft.com/en-us/sql/t-sql/statements/execute-as-clause-transact-sql)  seems to be failing me. For reference, the DBs in question are running on 2008 R2, but I'm recreating the behavior on my 2016 localhost. As well, the service account in question is a domain credential, but I've recreated the behavior with a SQL Auth credential for portability.  

### The Setup

    use [master]
    create database Prod;
    create database Stage;
    create login ServiceAccount with password='Password1234';
    go
    use Prod
    create table tbl1 ( i int );
    insert tbl1 select 1;
    go
    use Stage
    create user ServiceAccount for login ServiceAccount; 
    go
    create proc spLoadStageToProd as
    begin
    	insert Prod.dbo.tbl1(i)
    	select checksum(newid())%100; -- random number
    end;
    go
    grant execute on spLoadStageToProd to ServiceAccount;
    go

### The Testing

From the Stage database, exec spLoadStageToProd; succeeds. Predictably, exec as login = 'ServiceAccount'; exec spLoadStageToProd; fails with the error... 

    Msg 229, Level 14, State 5, Procedure spLoadStageToProd, Line 1 [Batch Start Line 21]
    The EXECUTE permission was denied on the object 'spLoadStageToProd', database 'Stage', schema 'dbo'.

Okay, so I'll try execute as owner so that the proc has the permissions it needs to do the work but the (*developer who has the password for*) ServiceAccount doesn't get to muck about in my Production area. 

    alter proc spLoadStageToProd
    with execute as owner
    as
    begin
    	insert Prod.dbo.tbl1(i)
    	select checksum(newid())%100; -- random number
    end;
    go

Shoot! Well now a simple test from Staging of exec spLoadStageToProd; returns the error: 

    Msg 916, Level 14, State 1, Procedure spLoadStageToProd, Line 5 [Batch Start Line 35]
    The server principal "DOMAIN\peter" is not able to access the database "Prod" under the current security context.

"DOMAIN\peter" is of course me: the doof with sysadmin server role... 

Well that's weird enough... I tried alter authorization on object::spLoadStageToProd to dbo; but the same error (Msg 916) pops up. What's more... exec as login = 'ServiceAccount'; exec spLoadStageToProd; now returns...

    Msg 229, Level 14, State 5, Procedure spLoadStageToProd, Line 1 [Batch Start Line 37]
    The EXECUTE permission was denied on the object 'spLoadStageToProd', database 'Stage', schema 'dbo'.

Screw it! alter authorization on object::spLoadStageToProd to sa;...

    Msg 15151, Level 16, State 1, Line 41
    Cannot find the user 'sa', because it does not exist or you do not have permission.

...

...

...[sad](https://media.giphy.com/media/Jq7y34Hgfy01y/giphy.gif) .

So... clearly I'm misunderstanding something fundamental. I tried enabling [cross-db ownership chaining](https://msdn.microsoft.com/en-us/library/bb669059(v=vs.110).aspx)  just in case that was the sticky wicket but no luck. After fruitless googling and a quick scan of [these](https://dba.stackexchange.com/questions/19324/cross-database-chaining-vs-trustworthy-option)  [two](https://dba.stackexchange.com/questions/152931/stored-procedure-security-with-execute-as-cross-database-queries-and-module-si)  dba.se questions, I'm pretty stuck. Where am I going wrong?

# How do I get this SProc to run on elevated cross-database permissions regardless of who calls it? 

The project that precipitated this question is an iterative deprecation so I think cert-signing may end up being a rather large administrative overhead as time goes on.

If it is possible to use this stored proc as a wrapper to execute restricted actions agnostic of _who_ calls it, that's the end-goal.

I am confident that the SProc cannot be improperly modified, so anything that executes from inside it may be highly permissioned - in the hopes that I don't need to administer perms for the ServiceAccount one-by-one.

----

### Courtesy Cleanup Script

    revert;
    use [master]
    go
    drop database Prod,Stage;
    drop login ServiceAccount;
    go


                        
Asked by Peter Vandivier (5678 rep)
Apr 20, 2017, 08:58 PM
Last activity: Apr 21, 2017, 04:37 PM
Cross-Database Impersonation Fail for Service Account

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