Use CommonCrypto CSPRNG for GetTempFileName on macOS

In the Unix build use the existing calculation of IsMac to determine if
Interop.Crypto (powered by OpenSSL) or CommonCrypto should be used
for the CSPRNG.

GetTempFileName is the most often reported hit of a failure in Interop+Crypto.cctor
, but that didn't benefit from when the macOS
implementation of System.Security.Cryptography.RandomNumberGenerator
changed to use CommonCrypto (via the new Apple-specific shim).

This rectifies that, and should take a significant burden off of the first run
experiences for macOS users who have not installed OpenSSL in a manner
where we can find it.

Author: bartonjs

src/Common/src/Interop/OSX/Interop.CommonCrypto.cs

@@ -0,0 +1,18 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.InteropServices;
+
+internal static partial class Interop
+{
+    // Direct support on top of Apple CommonCrypto.
+    // In general, this should not be used, the System.Security.Cryptography.Native.Apple shim
+    // being preferred. But when there is a layering complication, or other compelling reason,
+    // then this can be used directly.
+    internal static partial class CommonCrypto
+    {
+        [DllImport(Libraries.LibSystemCommonCrypto)]
+        internal static unsafe extern int CCRandomGenerateBytes(byte* bytes, int byteCount);
+    }
+}

src/Common/src/Interop/OSX/Interop.Libraries.cs

@@ -9,6 +9,7 @@ private static partial class Libraries
         internal const string CoreFoundationLibrary = "/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation";
         internal const string CoreServicesLibrary   = "/System/Library/Frameworks/CoreServices.framework/CoreServices";
         internal const string libproc = "libproc";
+        internal const string LibSystemCommonCrypto = "/usr/lib/system/libcommonCrypto";
         internal const string LibSystemKernel = "/usr/lib/system/libsystem_kernel";
         internal const string SystemConfigurationLibrary = "/System/Library/Frameworks/SystemConfiguration.framework/SystemConfiguration";
         internal const string AppleCryptoNative = "System.Security.Cryptography.Native.Apple";

src/System.Runtime.Extensions/src/System.Runtime.Extensions.csproj

@@ -117,6 +117,12 @@
   <ItemGroup Condition=" '$(TargetsUnix)' == 'true' ">
     <Compile Include="System\Diagnostics\Stopwatch.Unix.cs" />
     <Compile Include="System\IO\Path.Unix.cs" />
+    <Compile Include="$(CommonPath)\Interop\OSX\Interop.Libraries.cs">
+      <Link>Common\Interop\OSX\Interop.Libraries.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)\Interop\OSX\Interop.CommonCrypto.cs">
+      <Link>Common\Interop\OSX\Interop.CommonCrypto.cs</Link>
+    </Compile>
     <Compile Include="$(CommonPath)\Interop\Unix\Interop.Libraries.cs">
       <Link>Common\Interop\Unix\Interop.Libraries.cs</Link>
     </Compile>
@@ -135,6 +141,9 @@
     <Compile Include="$(CommonPath)\Interop\Unix\System.Native\Interop.GetTimestamp.cs">
       <Link>Common\Interop\Unix\System.Native\Interop.GetTimestamp.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)\Interop\Unix\System.Native\Interop.GetUnixName.cs">
+      <Link>Common\Interop\Unix\System.Native\Interop.GetUnixName.cs</Link>
+</Compile>
     <Compile Include="$(CommonPath)\Interop\Unix\System.Native\Interop.MksTemps.cs">
       <Link>Common\Interop\Unix\System.Native\Interop.MksTemps.cs</Link>
     </Compile>
@@ -188,4 +197,4 @@
     <None Include="project.json" />
   </ItemGroup>
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
-</Project>
+</Project>

src/System.Runtime.Extensions/src/System/IO/Path.Unix.cs

@@ -205,6 +205,29 @@ public static string GetPathRoot(string path)
         }
 
         private static unsafe void GetCryptoRandomBytes(byte* bytes, int byteCount)
+        {
+            if (IsMac)
+            {
+                GetCryptoRandomBytesApple(bytes, byteCount);
+            }
+            else
+            {
+                GetCryptoRandomBytesOpenSsl(bytes, byteCount);
+            }
+        }
+
+        private static unsafe void GetCryptoRandomBytesApple(byte* bytes, int byteCount)
+        {
+            Debug.Assert(bytes != null);
+            Debug.Assert(byteCount >= 0);
+
+            if (Interop.CommonCrypto.CCRandomGenerateBytes(bytes, byteCount) != 0)
+            {
+                throw new InvalidOperationException(SR.InvalidOperation_Cryptography);
+            }
+        }
+
+        private static unsafe void GetCryptoRandomBytesOpenSsl(byte* bytes, int byteCount)
         {
             Debug.Assert(bytes != null);
             Debug.Assert(byteCount >= 0);
@@ -214,5 +237,9 @@ private static unsafe void GetCryptoRandomBytes(byte* bytes, int byteCount)
                 throw new InvalidOperationException(SR.InvalidOperation_Cryptography);
             }
         }
+
+        // This lives as an internal property on Environment in master after forking for release/1.1.0
+        // It is copied here only for the backport and release branch fix.
+        private static readonly bool IsMac = Interop.Sys.GetUnixName() == "OSX";
     }
 }