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Fix crash in GSSAPI on macOS #71484

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merged 2 commits into from
Jul 1, 2022
Merged

Fix crash in GSSAPI on macOS #71484

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00b2786
On macOS the gss_accept_sec_context/gss_init_sec_context APIs release…
filipnavara Jun 30, 2022
2683d57
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filipnavara Jul 1, 2022
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306 changes: 119 additions & 187 deletions src/libraries/Common/src/System/Net/Security/NegotiateStreamPal.Unix.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -85,146 +85,6 @@ private static int GssUnwrap(
}
}

private static bool GssInitSecurityContext(
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@filipnavara filipnavara Jun 30, 2022 •
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The GssInitSecurityContext and GssAcceptSecurityContext methods are folded into the caller. This made updating the handles substantially easier. I also removed the code that threw GssApiException only to catch it one method above in the stack and convert it to reported status code.

ref SafeGssContextHandle? context,
SafeGssCredHandle credential,
bool isNtlm,
ChannelBinding? channelBinding,
SafeGssNameHandle? targetName,
Interop.NetSecurityNative.GssFlags inFlags,
ReadOnlySpan<byte> buffer,
out byte[]? outputBuffer,
out uint outFlags,
out bool isNtlmUsed)
{
outputBuffer = null;
outFlags = 0;

// EstablishSecurityContext is called multiple times in a session.
// In each call, we need to pass the context handle from the previous call.
// For the first call, the context handle will be null.
bool newContext = false;
if (context == null)
{
newContext = true;
context = new SafeGssContextHandle();
}

Interop.NetSecurityNative.GssBuffer token = default(Interop.NetSecurityNative.GssBuffer);
Interop.NetSecurityNative.Status status;

try
{
Interop.NetSecurityNative.Status minorStatus;

if (channelBinding != null)
{
// If a TLS channel binding token (cbt) is available then get the pointer
// to the application specific data.
int appDataOffset = Marshal.SizeOf<SecChannelBindings>();
Debug.Assert(appDataOffset < channelBinding.Size);
IntPtr cbtAppData = channelBinding.DangerousGetHandle() + appDataOffset;
int cbtAppDataSize = channelBinding.Size - appDataOffset;
status = Interop.NetSecurityNative.InitSecContext(out minorStatus,
credential,
ref context,
isNtlm,
cbtAppData,
cbtAppDataSize,
targetName,
(uint)inFlags,
buffer,
ref token,
out outFlags,
out isNtlmUsed);
}
else
{
status = Interop.NetSecurityNative.InitSecContext(out minorStatus,
credential,
ref context,
isNtlm,
targetName,
(uint)inFlags,
buffer,
ref token,
out outFlags,
out isNtlmUsed);
}

if ((status != Interop.NetSecurityNative.Status.GSS_S_COMPLETE) &&
(status != Interop.NetSecurityNative.Status.GSS_S_CONTINUE_NEEDED))
{
if (newContext)
{
context.Dispose();
context = null;
}
throw new Interop.NetSecurityNative.GssApiException(status, minorStatus);
}

outputBuffer = token.ToByteArray();
}
finally
{
token.Dispose();
}

return status == Interop.NetSecurityNative.Status.GSS_S_COMPLETE;
}

private static bool GssAcceptSecurityContext(
ref SafeGssContextHandle? context,
SafeGssCredHandle credential,
ReadOnlySpan<byte> buffer,
out byte[] outputBuffer,
out uint outFlags,
out bool isNtlmUsed)
{
Debug.Assert(credential != null);

bool newContext = false;
if (context == null)
{
newContext = true;
context = new SafeGssContextHandle();
}

Interop.NetSecurityNative.GssBuffer token = default(Interop.NetSecurityNative.GssBuffer);
Interop.NetSecurityNative.Status status;

try
{
Interop.NetSecurityNative.Status minorStatus;
status = Interop.NetSecurityNative.AcceptSecContext(out minorStatus,
credential,
ref context,
buffer,
ref token,
out outFlags,
out isNtlmUsed);

if ((status != Interop.NetSecurityNative.Status.GSS_S_COMPLETE) &&
(status != Interop.NetSecurityNative.Status.GSS_S_CONTINUE_NEEDED))
{
if (newContext)
{
context.Dispose();
context = null;
}
throw new Interop.NetSecurityNative.GssApiException(status, minorStatus);
}

outputBuffer = token.ToByteArray();
}
finally
{
token.Dispose();
}

return status == Interop.NetSecurityNative.Status.GSS_S_COMPLETE;
}

private static string GssGetUser(
ref SafeGssContextHandle? context)
{
Expand Down Expand Up @@ -287,27 +147,70 @@ private static SecurityStatusPal EstablishSecurityContext(
context = new SafeDeleteNegoContext(credential, targetName!);
}

Interop.NetSecurityNative.GssBuffer token = default(Interop.NetSecurityNative.GssBuffer);
Interop.NetSecurityNative.Status status;
Interop.NetSecurityNative.Status minorStatus;
SafeDeleteNegoContext negoContext = (SafeDeleteNegoContext)context;
SafeGssContextHandle contextHandle = negoContext.GssContext;
try
{
Interop.NetSecurityNative.GssFlags inputFlags =
ContextFlagsAdapterPal.GetInteropFromContextFlagsPal(inFlags, isServer: false);
uint outputFlags;
bool isNtlmUsed;
SafeGssContextHandle? contextHandle = negoContext.GssContext;
bool done = GssInitSecurityContext(
ref contextHandle,
credential.GssCredential,
isNtlmOnly,
channelBinding,
negoContext.TargetName,
inputFlags,
incomingBlob,
out resultBuffer,
out outputFlags,
out isNtlmUsed);

if (done)

if (channelBinding != null)
{
// If a TLS channel binding token (cbt) is available then get the pointer
// to the application specific data.
int appDataOffset = Marshal.SizeOf<SecChannelBindings>();
Debug.Assert(appDataOffset < channelBinding.Size);
IntPtr cbtAppData = channelBinding.DangerousGetHandle() + appDataOffset;
int cbtAppDataSize = channelBinding.Size - appDataOffset;
status = Interop.NetSecurityNative.InitSecContext(out minorStatus,
credential.GssCredential,
ref contextHandle,
isNtlmOnly,
cbtAppData,
cbtAppDataSize,
negoContext.TargetName,
(uint)inputFlags,
incomingBlob,
ref token,
out outputFlags,
out isNtlmUsed);
}
else
{
status = Interop.NetSecurityNative.InitSecContext(out minorStatus,
credential.GssCredential,
ref contextHandle,
isNtlmOnly,
negoContext.TargetName,
(uint)inputFlags,
incomingBlob,
ref token,
out outputFlags,
out isNtlmUsed);
}

if ((status != Interop.NetSecurityNative.Status.GSS_S_COMPLETE) &&
(status != Interop.NetSecurityNative.Status.GSS_S_CONTINUE_NEEDED))
{
if (negoContext.GssContext.IsInvalid)
{
context.Dispose();
}

Interop.NetSecurityNative.GssApiException gex = new Interop.NetSecurityNative.GssApiException(status, minorStatus);
if (NetEventSource.Log.IsEnabled()) NetEventSource.Error(null, gex);
resultBuffer = Array.Empty<byte>();
return new SecurityStatusPal(GetErrorCode(gex), gex);
}

resultBuffer = token.ToByteArray();

if (status == Interop.NetSecurityNative.Status.GSS_S_COMPLETE)
{
if (NetEventSource.Log.IsEnabled())
{
Expand All @@ -322,17 +225,9 @@ private static SecurityStatusPal EstablishSecurityContext(
Debug.Assert(resultBuffer != null, "Unexpected null buffer returned by GssApi");
outFlags = ContextFlagsAdapterPal.GetContextFlagsPalFromInterop(
(Interop.NetSecurityNative.GssFlags)outputFlags, isServer: false);
Debug.Assert(negoContext.GssContext == null || contextHandle == negoContext.GssContext);

// Save the inner context handle for further calls to NetSecurity
Debug.Assert(negoContext.GssContext == null || contextHandle == negoContext.GssContext);
if (null == negoContext.GssContext)
{
negoContext.SetGssContext(contextHandle!);
}

SecurityStatusPalErrorCode errorCode = done ?
(negoContext.IsNtlmUsed && resultBuffer.Length > 0 ? SecurityStatusPalErrorCode.OK : SecurityStatusPalErrorCode.CompleteNeeded) :
SecurityStatusPalErrorCode errorCode = status == Interop.NetSecurityNative.Status.GSS_S_COMPLETE ?
SecurityStatusPalErrorCode.OK :
SecurityStatusPalErrorCode.ContinueNeeded;
return new SecurityStatusPal(errorCode);
}
Expand All @@ -341,6 +236,22 @@ private static SecurityStatusPal EstablishSecurityContext(
if (NetEventSource.Log.IsEnabled()) NetEventSource.Error(null, ex);
return new SecurityStatusPal(SecurityStatusPalErrorCode.InternalError, ex);
}
finally
{
token.Dispose();

// Save the inner context handle for further calls to NetSecurity
//
// For the first call `negoContext.GssContext` is invalid and we expect the
// inital handle to be returned from InitSecContext. For any subsequent
// call the handle should stay the same or it can be destroyed by the native
// InitSecContext call.
Debug.Assert(
negoContext.GssContext == contextHandle ||
negoContext.GssContext.IsInvalid ||
contextHandle.IsInvalid);
negoContext.SetGssContext(contextHandle);
}
}

internal static SecurityStatusPal InitializeSecurityContext(
Expand Down Expand Up @@ -388,33 +299,44 @@ internal static SecurityStatusPal AcceptSecurityContext(
securityContext ??= new SafeDeleteNegoContext((SafeFreeNegoCredentials)credentialsHandle!);

SafeDeleteNegoContext negoContext = (SafeDeleteNegoContext)securityContext;
SafeGssContextHandle contextHandle = negoContext.GssContext;
Interop.NetSecurityNative.GssBuffer token = default(Interop.NetSecurityNative.GssBuffer);
try
{
SafeGssContextHandle? contextHandle = negoContext.GssContext;
bool done = GssAcceptSecurityContext(
ref contextHandle,
negoContext.AcceptorCredential,
incomingBlob,
out resultBlob,
out uint outputFlags,
out bool isNtlmUsed);

Debug.Assert(resultBlob != null, "Unexpected null buffer returned by GssApi");
Debug.Assert(negoContext.GssContext == null || contextHandle == negoContext.GssContext);
Interop.NetSecurityNative.Status status;
Interop.NetSecurityNative.Status minorStatus;
status = Interop.NetSecurityNative.AcceptSecContext(out minorStatus,
negoContext.AcceptorCredential,
ref contextHandle,
incomingBlob,
ref token,
out uint outputFlags,
out bool isNtlmUsed);

// Save the inner context handle for further calls to NetSecurity
Debug.Assert(negoContext.GssContext == null || contextHandle == negoContext.GssContext);
if (null == negoContext.GssContext)
if ((status != Interop.NetSecurityNative.Status.GSS_S_COMPLETE) &&
(status != Interop.NetSecurityNative.Status.GSS_S_CONTINUE_NEEDED))
{
negoContext.SetGssContext(contextHandle!);
if (negoContext.GssContext.IsInvalid)
{
contextHandle.Dispose();
}

Interop.NetSecurityNative.GssApiException gex = new Interop.NetSecurityNative.GssApiException(status, minorStatus);
if (NetEventSource.Log.IsEnabled()) NetEventSource.Error(null, gex);
resultBlobLength = 0;
return new SecurityStatusPal(GetErrorCode(gex), gex);
}

resultBlob = token.ToByteArray();

Debug.Assert(resultBlob != null, "Unexpected null buffer returned by GssApi");

contextFlags = ContextFlagsAdapterPal.GetContextFlagsPalFromInterop(
(Interop.NetSecurityNative.GssFlags)outputFlags, isServer: true);
resultBlobLength = resultBlob.Length;

SecurityStatusPalErrorCode errorCode;
if (done)
if (status == Interop.NetSecurityNative.Status.GSS_S_COMPLETE)
{
if (NetEventSource.Log.IsEnabled())
{
Expand All @@ -423,7 +345,7 @@ internal static SecurityStatusPal AcceptSecurityContext(
}

negoContext.SetAuthenticationPackage(isNtlmUsed);
errorCode = (isNtlmUsed && resultBlob.Length > 0) ? SecurityStatusPalErrorCode.OK : SecurityStatusPalErrorCode.CompleteNeeded;
errorCode = SecurityStatusPalErrorCode.OK;
}
else
{
Expand All @@ -432,18 +354,28 @@ internal static SecurityStatusPal AcceptSecurityContext(

return new SecurityStatusPal(errorCode);
}
catch (Interop.NetSecurityNative.GssApiException gex)
{
if (NetEventSource.Log.IsEnabled()) NetEventSource.Error(null, gex);
resultBlobLength = 0;
return new SecurityStatusPal(GetErrorCode(gex), gex);
}
catch (Exception ex)
{
if (NetEventSource.Log.IsEnabled()) NetEventSource.Error(null, ex);
resultBlobLength = 0;
return new SecurityStatusPal(SecurityStatusPalErrorCode.InternalError, ex);
}
finally
{
token.Dispose();

// Save the inner context handle for further calls to NetSecurity
//
// For the first call `negoContext.GssContext` is invalid and we expect the
// inital handle to be returned from AcceptSecContext. For any subsequent
// call the handle should stay the same or it can be destroyed by the native
// AcceptSecContext call.
Debug.Assert(
negoContext.GssContext == contextHandle ||
negoContext.GssContext.IsInvalid ||
contextHandle.IsInvalid);
negoContext.SetGssContext(contextHandle);
}
}

// https://www.gnu.org/software/gss/reference/gss.pdf (page 25)
Expand Down
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