Skip certificates we can't read when populating machine store. (#29973)

* Skip certificates we can't read when populating machine store.

This is a regression in 2.1.0 (https://github.com/dotnet/corefx/pull/29351).

Fixes https://github.com/dotnet/corefx/issues/29942.

* Add test

* Assert chmod returns 0

* Skip test on OSX

* Add valid content to the unreadable cert file

4 files changed, 131 insertions, 2 deletions

diff --git a/src/System.Security.Cryptography.X509Certificates/src/Internal/Cryptography/Pal.Unix/StorePal.cs b/src/System.Security.Cryptography.X509Certificates/src/Internal/Cryptography/Pal.Unix/StorePal.cs
index 3c3cdb20c5..57b8f025b8 100644
--- a/src/System.Security.Cryptography.X509Certificates/src/Internal/Cryptography/Pal.Unix/StorePal.cs
+++ b/src/System.Security.Cryptography.X509Certificates/src/Internal/Cryptography/Pal.Unix/StorePal.cs
@@ -254,7 +254,12 @@ namespace Internal.Cryptography.Pal
             {
                 using (SafeBioHandle fileBio = Interop.Crypto.BioNewFile(file.FullName, "rb"))
                 {
-                    Interop.Crypto.CheckValidOpenSslHandle(fileBio);
+                    // The handle may be invalid, for example when we don't have read permission for the file.
+                    if (fileBio.IsInvalid)
+                    {
+                        Interop.Crypto.ErrClearError();
+                        continue;
+                    }
 
                     ICertificatePal pal;
 
diff --git a/src/System.Security.Cryptography.X509Certificates/tests/System.Security.Cryptography.X509Certificates.Tests.csproj b/src/System.Security.Cryptography.X509Certificates/tests/System.Security.Cryptography.X509Certificates.Tests.csproj
index 9c209605c3..9c63bf6fca 100644
--- a/src/System.Security.Cryptography.X509Certificates/tests/System.Security.Cryptography.X509Certificates.Tests.csproj
+++ b/src/System.Security.Cryptography.X509Certificates/tests/System.Security.Cryptography.X509Certificates.Tests.csproj
@@ -91,6 +91,12 @@
     <Compile Include="TestEnvironmentConfiguration.Unix.cs" />
   </ItemGroup>
   <ItemGroup>
+    <ProjectReference Include="$(CommonTestPath)\System\Diagnostics\RemoteExecutorConsoleApp\RemoteExecutorConsoleApp.csproj">
+      <Project>{69e46a6f-9966-45a5-8945-2559fe337827}</Project>
+      <Name>RemoteExecutorConsoleApp</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <ItemGroup>
     <SupplementalTestData Include="$(PackagesDir)system.security.cryptography.x509certificates.testdata\1.0.2-prerelease\content\**\*.*" />
   </ItemGroup>
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
diff --git a/src/System.Security.Cryptography.X509Certificates/tests/TestData.cs b/src/System.Security.Cryptography.X509Certificates/tests/TestData.cs
index 25b55d437b..ff8c1614be 100644
--- a/src/System.Security.Cryptography.X509Certificates/tests/TestData.cs
+++ b/src/System.Security.Cryptography.X509Certificates/tests/TestData.cs
@@ -82,6 +82,78 @@ Og7vtpU6pzjkJZIIpohmgg==
 -----END CERTIFICATE-----
 ");
 
+        // 'cert.pem' generated using 'openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365'
+        public static readonly byte[] SelfSigned1PemBytes = ByteUtils.AsciiBytes(
+            @"-----BEGIN CERTIFICATE-----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==
+-----END CERTIFICATE-----
+");
+
+        // 'cert.pem' generated using 'openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365'
+        public static readonly byte[] SelfSigned2PemBytes = ByteUtils.AsciiBytes(
+            @"-----BEGIN CERTIFICATE-----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==
+-----END CERTIFICATE-----
+");
+
+        // 'cert.pem' generated using 'openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365'
+        public static readonly byte[] SelfSigned3PemBytes = ByteUtils.AsciiBytes(
+            @"-----BEGIN CERTIFICATE-----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==
+-----END CERTIFICATE-----
+");
+
         public const string PfxDataPassword = "12345";
 
         public static SecureString CreatePfxDataPasswordSecureString()
diff --git a/src/System.Security.Cryptography.X509Certificates/tests/X509StoreTests.cs b/src/System.Security.Cryptography.X509Certificates/tests/X509StoreTests.cs
index 2bc94e2fec..151067587b 100644
--- a/src/System.Security.Cryptography.X509Certificates/tests/X509StoreTests.cs
+++ b/src/System.Security.Cryptography.X509Certificates/tests/X509StoreTests.cs
@@ -2,11 +2,14 @@
 // 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.Diagnostics;
+using System.IO;
+using System.Runtime.InteropServices;
 using Xunit;
 
 namespace System.Security.Cryptography.X509Certificates.Tests
 {
-    public class X509StoreTests
+    public class X509StoreTests : RemoteExecutorTestBase
     {
         [Fact]
         public static void OpenMyStore()
@@ -496,5 +499,48 @@ namespace System.Security.Cryptography.X509Certificates.Tests
                 Assert.Equal(0, store.Certificates.Count);
             }
         }
+
+        [Fact]
+        [PlatformSpecific(TestPlatforms.Linux)] // Windows/OSX doesn't use SSL_CERT_{DIR,FILE}.
+        private void X509Store_MachineStoreLoadSkipsInvalidFiles()
+        {
+            // We create a folder for our machine store and use it by setting SSL_CERT_{DIR,FILE}.
+            // In the store we'll add some invalid files, but we start and finish with a valid file.
+            // This is to account for the order in which the store is populated.
+            string sslCertDir = GetTestFilePath();
+            Directory.CreateDirectory(sslCertDir);
+
+            // Valid file.
+            File.WriteAllBytes(Path.Combine(sslCertDir, "0.pem"), TestData.SelfSigned1PemBytes);
+
+            // File with invalid content.
+            File.WriteAllText(Path.Combine(sslCertDir, "1.pem"), "This is not a valid cert");
+
+            // File which is not readable by the current user.
+            string unreadableFileName = Path.Combine(sslCertDir, "2.pem");
+            File.WriteAllBytes(unreadableFileName, TestData.SelfSigned2PemBytes);
+            Assert.Equal(0, chmod(unreadableFileName, 0));
+
+            // Valid file.
+            File.WriteAllBytes(Path.Combine(sslCertDir, "3.pem"), TestData.SelfSigned3PemBytes);
+
+            var psi = new ProcessStartInfo();
+            psi.Environment.Add("SSL_CERT_DIR", sslCertDir);
+            psi.Environment.Add("SSL_CERT_FILE", "/nonexisting");
+            RemoteInvoke(() =>
+            {
+                using (var store = new X509Store(StoreName.Root, StoreLocation.LocalMachine))
+                {
+                    store.Open(OpenFlags.OpenExistingOnly);
+
+                    // Check nr of certificates in store.
+                    Assert.Equal(2, store.Certificates.Count);
+                }
+                return SuccessExitCode;
+            }, new RemoteInvokeOptions { StartInfo = psi }).Dispose();
+        }
+
+        [DllImport("libc")]
+        private static extern int chmod(string path, int mode);
     }
 }