Fix key exchange hang for outofproc transports #11380

PaulHigin · 2019-12-17T16:53:42Z

PR Summary

This PR fixes the remoting key exchange hang in OutOfProc transport connections, when transferring SecureString objects.
Fixes issue: #259

PR Context

When a SecureString object is transferred over the remoting layer, a key exchange algorithm is lazily run so that the contents of the SecureString can be encrypted. This is not strictly necessary since both WinRM and SSH remoting channels already encrypt data on the wire by default. But the key exchange must remain for compatibility reasons.

The hang occurs when the target sends an encrypted SecureString object to the client for the first time. The client begins a key exchange handshake with the target so that it can handle the object. This works fine for WinRM based remote connections because the client processes session and command protocol messages on different threads. But the OutOfProc based transport implementations process client protocol messages on a single thread, and the lazily initiated key exchange results in a deadlock.

The fix is to update the OutOfProc transport manager base class to detect and process command and session client protocol messages on separate threads.

This is not a low risk change since it affects four remote implementations that are based on the OutOfProc transport: background jobs, PowerShellDirect, named pipes, SSH.

Repro Steps:

$session = New-PSSession -Host localhost
Invoke-Command $session { $ss = ConvertTo-SecureString "Hello" -AsPlainText -Force }
Invoke-Command $session { $ss }

#Result
Hang

#Expected
SecureString object to be returned.

PR Checklist

…essing threads for session and command protocol messages.

src/System.Management.Automation/engine/remoting/fanin/OutOfProcTransportManager.cs

SteveL-MSFT

One NIT

src/System.Management.Automation/engine/remoting/fanin/OutOfProcTransportManager.cs

…nsport-key-hang

src/System.Management.Automation/engine/remoting/fanin/OutOfProcTransportManager.cs

SteveL-MSFT · 2019-12-17T18:21:29Z

@PaulHigin merge upstream/master tp pick up fix for the nulconditional tests

…nsport-key-hang

src/System.Management.Automation/engine/remoting/fanin/OutOfProcTransportManager.cs

…nsport-key-hang

TylerLeonhardt · 2019-12-17T20:20:41Z

This will probably fix Azure/azure-functions-powershell-worker#259

daxian-dbw · 2019-12-18T01:36:45Z

Will this issue be considered for GA? Otherwise, the Azure Function issue won't really be resolved until 7.1, which maybe a year later.

TylerLeonhardt · 2019-12-20T01:34:51Z

I would love for it to make it into GA.

invisibleaxm · 2020-01-23T02:53:24Z

Hello, just trying to understand, i see GA-approved for this PR, does it mean it will also solve for the Azure Functions issue ? (Azure/azure-functions-powershell-worker#259)

daxian-dbw · 2020-01-23T22:16:29Z

Yes, this will address that issue, as soon as the Azure Functions team adopts PowerShell 7 in their runtime.

Fix key exchange hang for outofproc transports by using separate proc…

ca0980a

…essing threads for session and command protocol messages.

ghost assigned anmenaga Dec 17, 2019

PaulHigin requested a review from SteveL-MSFT December 17, 2019 16:55