CipherSuitesPolicy constructor throws PlatformNotSupportedException on Linux with OpenSSL 1.1.1

[gunnarhelgason]

Description

According to the documentation, it should be possible to use the CipherSuitesPolicy class on Linux systems with OpenSSL 1.1.1 or higher or macOS. However, when using .NET 6 on Linux with OpenSSL 1.1.1, PlatformNotSupportedException is thrown. The same code works fine when using .NET 5

Reproduction Steps

Run the following program:

using System.Net.Security;

namespace csptest
{
    public static class Program
    {
        public static void Main()
        {
            var cipherSuitesPolicy = new CipherSuitesPolicy(new TlsCipherSuite[] { });
        }
    }
}

Expected behavior

Program completes successfully

Actual behavior

Exception is thrown:

Unhandled exception. System.PlatformNotSupportedException: CipherSuitesPolicy is not supported on this platform.
   at System.Net.Security.CipherSuitesPolicyPal..ctor(IEnumerable`1 allowedCipherSuites)
   at System.Net.Security.CipherSuitesPolicy..ctor(IEnumerable`1 allowedCipherSuites)
   at csptest.Program.Main() in /home/gth/csptest/Program.cs:line 9

Regression?

Seems like it, as it works fine on .NET 5

Known Workarounds

No response

Configuration

.NET
.NET 6

dotnet --list-sdks
6.0.100 [/usr/share/dotnet/sdk]
dotnet --list-runtimes
Microsoft.AspNetCore.App 6.0.0 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.0 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

OpenSSL
OpenSSL 1.1.1f

openssl version
OpenSSL 1.1.1f  31 Mar 2020

OS
Ubuntu 20.04.3 LTS x86_64 (completely clean install)

lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 20.04.3 LTS
Release:	20.04
Codename:	focal

Same issue also occurs on Ubuntu 21.10

Other information

No response

Tagging subscribers to this area: @dotnet/ncl, @vcsjones
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

According to the documentation, it should be possible to use the CipherSuitesPolicy class on Linux systems with OpenSSL 1.1.1 or higher or macOS. However, when using .NET 6 on Linux with OpenSSL 1.1.1, PlatformNotSupportedException is thrown. The same code completes successfully when using .NET 5

Reproduction Steps

Run the following program:

using System.Net.Security;

namespace csptest
{
    public static class Program
    {
        public static void Main()
        {
            var cipherSuitesPolicy = new CipherSuitesPolicy(new TlsCipherSuite[] { });
        }
    }
}

Expected behavior

Program completes successfully

Actual behavior

Exception is thrown:

Unhandled exception. System.PlatformNotSupportedException: CipherSuitesPolicy is not supported on this platform.
   at System.Net.Security.CipherSuitesPolicyPal..ctor(IEnumerable`1 allowedCipherSuites)
   at System.Net.Security.CipherSuitesPolicy..ctor(IEnumerable`1 allowedCipherSuites)
   at csptest.Program.Main() in /home/gth/csptest/Program.cs:line 9

Regression?

Works fine on .NET 5

Known Workarounds

No response

Configuration

.NET
.NET 6

dotnet --list-sdks
6.0.100 [/usr/share/dotnet/sdk]
dotnet --list-runtimes
Microsoft.AspNetCore.App 6.0.0 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.0 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

OpenSSL

openssl version
OpenSSL 1.1.1f  31 Mar 2020

OS
Ubuntu 20.04.3 LTS x86_64 (completely clean install)

lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 20.04.3 LTS
Release:	20.04
Codename:	focal

Same issue also occurs on Ubuntu 21.10

Other information

No response

Author:	gunnarhelgason
Assignees:	-
Labels:	area-System.Net.Security, untriaged
Milestone:	-

[vcsjones]

Hm, well, I can reproduce it on 21.10 using 6.0-RTM installed by binaries.

[wfurt]

There is something wrong with the loading. It works when I modify it as

using System.Net.Security;
using System.Net.Http;
using System;

namespace csptest
{
    public class Program
    {
        public static void Main()
        {
            try {
                var client = new HttpClient();
                _ = client.GetAsync("https://microsoft.com").GetAwaiter().GetResult();
            } catch { };

            var cipherSuitesPolicy = new CipherSuitesPolicy(new TlsCipherSuite[] { });
            Console.WriteLine("Policy OK");
        }
    }
}

API_EXISTS(SSL_CTX_set_ciphersuites) returns 0 and SSL_CTX_set_ciphersuites_ptr is null with the original code.
cc: @bartonjs

[bartonjs]

I wonder if the CipherSuitesPolicy ctor functionally depends on CryptoInitializer but doesn't actually cause it to run.

[wfurt]

It seems like the problem is ordering. I have two breakpoints and the following lldb/sos fragment is in order.

(lldb) bt
* thread #1, name = 'aa', stop reason = breakpoint 1.1
  * frame #0: 0x00007fffed4c849f libSystem.Security.Cryptography.Native.OpenSsl.so`CryptoNative_Tls13Supported at pal_ssl.c:581:87

(lldb) clrstack
OS Thread Id: 0x6a0c (1)
        Child SP               IP Call Site
00007FFFFFFFCB38 00007fffed4c849f [InlinedCallFrame: 00007fffffffcb38] Interop+Ssl.Tls13SupportedImpl()
00007FFFFFFFCB38 00007fff7d3e77cd [InlinedCallFrame: 00007fffffffcb38] Interop+Ssl.Tls13SupportedImpl()
00007FFFFFFFCB30 00007FFF7D3E77CD ILStubClass.IL_STUB_PInvoke()
00007FFFFFFFCBE0 00007FFF7D3E76F3 Interop+Ssl..cctor() [/home/furt/github/wfurt-runtime2/src/libraries/Common/src/Interop/Unix/System.Security.Cryptography.Native/Interop.Ssl.cs @ 146]
00007FFFFFFFD328 00007ffff68dc457 [HelperMethodFrame: 00007fffffffd328]
00007FFFFFFFD470 00007FFF7D3E70AA System.Net.Security.CipherSuitesPolicyPal..ctor(System.Collections.Generic.IEnumerable`1<System.Net.Security.TlsCipherSuite>) [/home/furt/github/wfurt-runtime2/src/libraries/System.Net.Security/src/System/Net/Security/CipherSuitesPolicyPal.Linux.cs @ 31]
00007FFFFFFFD5B0 00007FFF7D3E5F79 System.Net.Security.CipherSuitesPolicy..ctor(System.Collections.Generic.IEnumerable`1<System.Net.Security.TlsCipherSuite>) [/home/furt/github/wfurt-runtime2/src/libraries/System.Net.Security/src/System/Net/Security/CipherSuitesPolicy.cs @ 23]
00007FFFFFFFD5F0 00007FFF7D3E5A4D csptest.Program.Main() [/tmp/aa/Program.cs @ 18]


(lldb) bt
* thread #1, name = 'aa', stop reason = breakpoint 2.1
  * frame #0: 0x00007fffed4c78bf libSystem.Security.Cryptography.Native.OpenSsl.so`CryptoNative_EnsureLibSslInitialized at pal_ssl.c:127:61
    frame #1: 0x00007fff7d3f3e17

(lldb) clrstack
OS Thread Id: 0x6a0c (1)
        Child SP               IP Call Site
00007FFFFFFFC298 00007fffed4c78bf [InlinedCallFrame: 00007fffffffc298] Interop+Ssl.EnsureLibSslInitialized()
00007FFFFFFFC298 00007fff7d3f3e17 [InlinedCallFrame: 00007fffffffc298] Interop+Ssl.EnsureLibSslInitialized()
00007FFFFFFFC290 00007FFF7D3F3E17 ILStubClass.IL_STUB_PInvoke()
00007FFFFFFFC330 00007FFF7D3F3B50 Interop+SslInitializer..cctor() [/home/furt/github/wfurt-runtime2/src/libraries/Common/src/Interop/Unix/System.Net.Security.Native/Interop.Initialization.cs @ 28]
00007FFFFFFFCA88 00007ffff68dc457 [HelperMethodFrame: 00007fffffffca88]
00007FFFFFFFCBD0 00007FFF7D3F36E8 Interop+SslInitializer.Initialize() [/home/furt/github/wfurt-runtime2/src/libraries/Common/src/Interop/Unix/System.Net.Security.Native/Interop.Initialization.cs @ 38]
00007FFFFFFFCBE0 00007FFF7D3E771E Interop+Ssl..cctor() [/home/furt/github/wfurt-runtime2/src/libraries/Common/src/Interop/Unix/System.Net.Security.Native/Interop.Initialization.cs @ 16]
00007FFFFFFFD328 00007ffff68dc457 [HelperMethodFrame: 00007fffffffd328]
00007FFFFFFFD470 00007FFF7D3E70AA System.Net.Security.CipherSuitesPolicyPal..ctor(System.Collections.Generic.IEnumerable`1<System.Net.Security.TlsCipherSuite>) [/home/furt/github/wfurt-runtime2/src/libraries/System.Net.Security/src/System/Net/Security/CipherSuitesPolicyPal.Linux.cs @ 31]
00007FFFFFFFD5B0 00007FFF7D3E5F79 System.Net.Security.CipherSuitesPolicy..ctor(System.Collections.Generic.IEnumerable`1<System.Net.Security.TlsCipherSuite>) [/home/furt/github/wfurt-runtime2/src/libraries/System.Net.Security/src/System/Net/Security/CipherSuitesPolicy.cs @ 23]
00007FFFFFFFD5F0 00007FFF7D3E5A4D csptest.Program.Main() [/tmp/aa/Program.cs @ 18]

So the method on Ssl class is called sooner than static constructor for given class. None of the logic seems to change in 6.0.
Adding @stephentoub and @janvorli in case they have some more insight to the mystery.

[bartonjs]

runtime/src/libraries/Common/src/Interop/Unix/System.Security.Cryptography.Native/Interop.Ssl.cs

Lines 143 to 146 in e9036b0

	[DllImport(Libraries.CryptoNative, EntryPoint = "CryptoNative_Tls13Supported")]
	[return: MarshalAs(UnmanagedType.Bool)]
	private static extern bool Tls13SupportedImpl();
	internal static readonly bool Tls13Supported = Tls13SupportedImpl();

That uses a static field initializer to populate the value. I that runs before the explicit cctor. So this has probably always had an ordering dependency on waking up something from the main crypto codepaths first; just for one reason or another it never came up.

[wfurt]

I think you are right. The reason why it worked in 5.0 is

__attribute__((constructor))
static void InitializeOpenSSLShim()
{

so the function pointers were always loaded regardless of CryptoNative_EnsureLibSslInitialized being called.
That was removed in #46640.
cc: @VSadov

[bartonjs]

So the fix is probably just to delay call the routine

private static int s_tls13Supported;

internal static bool Tls13Supported
{
    get
    {
        if (s_tls13Supported == 0)
        {
          s_tls13Supported = Tls13SupportedImpl() ? 1 : -1;
        }

        return s_tls13Supported == 1;
    }
}

[wfurt]

That does work. I'm not sure how much we care about loosing readonly.

We could possibly fix up this particular in different ways (including the C PAL) But I'm wondering if we may have issues with other functions as well where somebody may (indirectly) call some functionality before fist SSL kicks in.