[System]: Epic: Client Certificate Support - Part Two.

This is the second and final part to bring Client Certificate support.
It needs to be landed on top of #8753 and #8756.

* `Mono.Security.Interface.IMonoSslStream`: Add `CanRenegotiate` and `RenegotiateAsync()`.

* `Mono.Security.Interface.MonoTlsSettings`: Add `DisallowUnauthenticatedCertificateRequest`.

* `AppleTlsContext`: fully support renegotiation.
  - we may now receive `SslStatus.PeerAuthCompleted` and `SslStatus.PeerClientCertRequested`
    during `Read()`.  It should in theory not happen during `Write()`, but I added it there
    as well just to be on the safe side.
  - `SetSessionOption()` may only be called before the initial handshake.

* `MobileAuthenticatedStream`: this is the major part of the work and the most complex one.
  - added a new `Operation` enum to keep track of what is going on and detect invalid state.
  - a renegotion may only be triggered while we're idle - that is no handshake, read or write
    operation is currently active.
  - `InternalWrite()` may now be called from `SSLRead()`, the new `Operation` tells us what
    is currently happening.
  - `ProcessHandshake()` now takes a `bool renegotiate` argument.
  - added sanity checks to `ProcessRead()` and `ProcessWrite()`.

* `MobileTlsContext.SelectClientCertificate()`: check for
  `MonoTlsSettings.DisallowUnauthenticatedCertificateRequest`

* `MonoTlsProviderFactory.InternalVersion`: bump the internal version number.

Tests have already been added to `web-tests/master`, they will auto-enable themselves when
using a Mono runtime that contains this code.

configure.ac

@@ -40,7 +40,7 @@ MONO_VERSION_BUILD=`echo $VERSION | cut -d . -f 3`
 # This can be reset to 0 when Mono's version number is bumped
 # since it's part of the corlib version (the prefix '1' in the full
 # version number is to ensure the number isn't treated as octal in C)
-MONO_CORLIB_COUNTER=6
+MONO_CORLIB_COUNTER=7
 MONO_CORLIB_VERSION=`printf "1%02d%02d%02d%03d" $MONO_VERSION_MAJOR $MONO_VERSION_MINOR 0 $MONO_CORLIB_COUNTER`
 
 AC_DEFINE_UNQUOTED(MONO_CORLIB_VERSION,$MONO_CORLIB_VERSION,[Version of the corlib-runtime interface])

mcs/class/Mono.Security/Mono.Security.Interface/IMonoSslStream.cs

@@ -208,6 +208,12 @@ public interface IMonoSslStream : IDisposable
 
 
 		MonoTlsConnectionInfo GetConnectionInfo ();
+
+		bool CanRenegotiate {
+			get;
+		}
+
+		Task RenegotiateAsync (CancellationToken cancellationToken);
 	}
 
 	interface IMonoSslStream2 : IMonoSslStream

mcs/class/Mono.Security/Mono.Security.Interface/MonoTlsProviderFactory.cs

@@ -182,9 +182,10 @@ public static IMonoSslStream GetMonoSslStream (HttpListenerContext context)
 		 *
 		 * - 1: everything up until May 2018
 		 * - 2: the new ServicePointScheduler changes have landed
+		 * - 3: full support for Client Certificates
 		 *
 		 */
-		internal const int InternalVersion = 2;
+		internal const int InternalVersion = 3;
 
 		#endregion
 	}

mcs/class/Mono.Security/Mono.Security.Interface/MonoTlsSettings.cs

@@ -100,6 +100,10 @@ public sealed class MonoTlsSettings
 			get; set;
 		}
 
+		public bool DisallowUnauthenticatedCertificateRequest {
+			get; set;
+		}
+
 		/*
 		 * If you set this here, then it will override 'ServicePointManager.SecurityProtocol'.
 		 */
@@ -189,6 +193,7 @@ public MonoTlsSettings Clone ()
 			CertificateValidationTime = other.CertificateValidationTime;
 			SendCloseNotify = other.SendCloseNotify;
 			ClientCertificateIssuers = other.ClientCertificateIssuers;
+			DisallowUnauthenticatedCertificateRequest = other.DisallowUnauthenticatedCertificateRequest;
 			if (other.TrustAnchors != null)
 				TrustAnchors = new X509CertificateCollection (other.TrustAnchors);
 			if (other.CertificateSearchPaths != null) {

mcs/class/System/Mono.AppleTls/AppleTlsContext.cs

@@ -56,7 +56,7 @@ class AppleTlsContext : MobileTlsContext
 		MonoTlsConnectionInfo connectionInfo;
 		bool isAuthenticated;
 		bool handshakeFinished;
-		// bool renegotiating;
+		bool renegotiating;
 		int handshakeStarted;
 
 		bool closed;
@@ -145,6 +145,24 @@ public override void StartHandshake ()
 
 			InitializeConnection ();
 
+			/*
+			 * SecureTransport is bugged OS X 10.5.8+ - renegotiation after
+			 * calling SetCertificate() will not work.
+			 *
+			 * We also cannot change options after the handshake has started,
+			 * so if you want to request a client certificate, it will happen
+			 * both during the initial handshake and during renegotiation.
+			 *
+			 * You may check 'SslStream.IsAuthenticated' (which will be false
+			 * during the initial handshake) from within your
+			 * 'LocalCertificateSelectionCallback' and return null to have the
+			 * callback invoked again during renegotiation.
+			 *
+			 * However, the first time your selection callback returns a client
+			 * certificate, that certificate will be used for the rest of the
+			 * session.
+			 */
+
 			SetSessionOption (SslSessionOption.BreakOnCertRequested, true);
 			SetSessionOption (SslSessionOption.BreakOnClientAuth, true);
 			SetSessionOption (SslSessionOption.BreakOnServerAuth, true);
@@ -174,7 +192,7 @@ public override void Flush ()
 
 		public override bool ProcessHandshake ()
 		{
-			if (handshakeFinished)
+			if (handshakeFinished && !renegotiating)
 				throw new NotSupportedException ("Handshake already finished.");
 
 			while (true) {
@@ -191,7 +209,9 @@ public override bool ProcessHandshake ()
 				} else if (status == SslStatus.WouldBlock) {
 					return false;
 				} else if (status == SslStatus.Success) {
+					Debug ("Handshake complete!");
 					handshakeFinished = true;
+					renegotiating = false;
 					return true;
 				}
 			}
@@ -320,6 +340,9 @@ void InitializeConnection ()
 			    !IPAddress.TryParse (TargetHost, out address)) {
 				PeerDomainName = ServerName;
 			}
+
+			if (Options.AllowRenegotiation)
+				SetSessionOption (SslSessionOption.AllowRenegotiation, true);
 		}
 
 		void InitializeSession ()
@@ -858,7 +881,19 @@ public override unsafe (int ret, bool wantMore) Read (byte[] buffer, int offset,
 					return (0, false);
 				}
 
-				CheckStatusAndThrow (status, SslStatus.WouldBlock, SslStatus.ClosedGraceful);
+				CheckStatusAndThrow (status, SslStatus.WouldBlock, SslStatus.ClosedGraceful,
+				                     SslStatus.PeerAuthCompleted, SslStatus.PeerClientCertRequested);
+
+				if (status == SslStatus.PeerAuthCompleted) {
+					Debug ($"Renegotiation complete: {GetSessionState ()}");
+					EvaluateTrust ();
+					return (0, true);
+				} else if (status == SslStatus.PeerClientCertRequested) {
+					Debug ($"Renegotiation asked for client certificate: {GetSessionState ()}");
+					ClientCertificateRequested ();
+					return (0, true);
+				}
+
 				var wantMore = status == SslStatus.WouldBlock;
 				return ((int)processed, wantMore);
 			} catch (Exception ex) {
@@ -890,7 +925,16 @@ public override unsafe (int ret, bool wantMore) Write (byte[] buffer, int offset
 
 				Debug ("Write done: {0} {1}", status, processed);
 
-				CheckStatusAndThrow (status, SslStatus.WouldBlock);
+				CheckStatusAndThrow (status, SslStatus.WouldBlock,
+				                     SslStatus.PeerAuthCompleted, SslStatus.PeerClientCertRequested);
+
+				if (status == SslStatus.PeerAuthCompleted) {
+					Debug ($"Renegotiation complete: {GetSessionState ()}");
+					EvaluateTrust ();
+				} else if (status == SslStatus.PeerClientCertRequested) {
+					Debug ($"Renegotiation asked for client certificate: {GetSessionState ()}");
+					ClientCertificateRequested ();
+				}
 
 				var wantMore = status == SslStatus.WouldBlock;
 				return ((int)processed, wantMore);
@@ -929,7 +973,7 @@ public override void Renegotiate ()
 
 			var status = SSLReHandshake (Handle);
 			CheckStatusAndThrow (status);
-			// renegotiating = true;
+			renegotiating = true;
 #endif
 		}
 

mcs/class/System/Mono.Btls/MonoBtlsContext.cs

@@ -137,6 +137,9 @@ public override void StartHandshake ()
 			} else {
 				ssl.SetServerName (ServerName);
 			}
+
+			if (Options.AllowRenegotiation)
+				ssl.SetRenegotiateMode (MonoBtlsSslRenegotiateMode.FREELY);
 		}
 
 		void SetPrivateCertificate (X509CertificateImplBtls privateCert)

mcs/class/System/Mono.Net.Security/AsyncProtocolRequest.cs

@@ -280,7 +280,7 @@ public AsyncHandshakeRequest (MobileAuthenticatedStream parent, bool sync)
 
 		protected override AsyncOperationStatus Run (AsyncOperationStatus status)
 		{
-			return Parent.ProcessHandshake (status);
+			return Parent.ProcessHandshake (status, false);
 		}
 	}
 
@@ -390,5 +390,17 @@ protected override AsyncOperationStatus Run (AsyncOperationStatus status)
 		}
 	}
 
+	class AsyncRenegotiateRequest : AsyncProtocolRequest
+	{
+		public AsyncRenegotiateRequest (MobileAuthenticatedStream parent)
+			: base (parent, false)
+		{
+		}
+
+		protected override AsyncOperationStatus Run (AsyncOperationStatus status)
+		{
+			return Parent.ProcessHandshake (status, true);
+		}
+	}
 }
 #endif