SSH Agent: Add support for OpenSSH for Windows

src/core/Bootstrap.cpp

@@ -16,6 +16,7 @@
  */
 
 #include "Bootstrap.h"
+#include "config-keepassx.h"
 #include "core/Config.h"
 #include "core/Translator.h"
 #include "gui/MessageBox.h"
@@ -26,6 +27,21 @@
 #undef MessageBox
 #endif
 
+#if defined(HAVE_RLIMIT_CORE)
+#include <sys/resource.h>
+#endif
+
+#if defined(HAVE_PR_SET_DUMPABLE)
+#include <sys/prctl.h>
+#endif
+
+#ifdef HAVE_PT_DENY_ATTACH
+// clang-format off
+#include <sys/types.h>
+#include <sys/ptrace.h>
+// clang-format on
+#endif
+
 namespace Bootstrap
 {
     /**
@@ -140,6 +156,8 @@ namespace Bootstrap
         HANDLE hToken = nullptr;
         PTOKEN_USER pTokenUser = nullptr;
         DWORD cbBufferSize = 0;
+        PSID pLocalSystemSid = nullptr;
+        DWORD pLocalSystemSidSize = SECURITY_MAX_SID_SIZE;
 
         // Access control list
         PACL pACL = nullptr;
@@ -166,8 +184,19 @@ namespace Bootstrap
             goto Cleanup;
         }
 
+        // Retrieve LocalSystem account SID
+        pLocalSystemSid = static_cast<PSID>(HeapAlloc(GetProcessHeap(), 0, pLocalSystemSidSize));
+        if (pLocalSystemSid == nullptr) {
+            goto Cleanup;
+        }
+
+        if (!CreateWellKnownSid(WinLocalSystemSid, nullptr, pLocalSystemSid, &pLocalSystemSidSize)) {
+            goto Cleanup;
+        }
+
         // Calculate the amount of memory that must be allocated for the DACL
-        cbACL = sizeof(ACL) + sizeof(ACCESS_ALLOWED_ACE) + GetLengthSid(pTokenUser->User.Sid);
+        cbACL = sizeof(ACL) + sizeof(ACCESS_ALLOWED_ACE) + GetLengthSid(pTokenUser->User.Sid)
+                + sizeof(ACCESS_ALLOWED_ACE) + GetLengthSid(pLocalSystemSid);
 
         // Create and initialize an ACL
         pACL = static_cast<PACL>(HeapAlloc(GetProcessHeap(), 0, cbACL));
@@ -189,6 +218,18 @@ namespace Bootstrap
             goto Cleanup;
         }
 
+#ifdef WITH_XC_SSHAGENT
+        // OpenSSH for Windows ssh-agent service is running as LocalSystem
+        if (!AddAccessAllowedAce(
+                pACL,
+                ACL_REVISION,
+                PROCESS_QUERY_INFORMATION | PROCESS_DUP_HANDLE, // just enough for ssh-agent
+                pLocalSystemSid // known LocalSystem sid
+                )) {
+            goto Cleanup;
+        }
+#endif
+
         // Set discretionary access control list
         bSuccess = ERROR_SUCCESS
                    == SetSecurityInfo(GetCurrentProcess(), // object handle
@@ -205,6 +246,9 @@ namespace Bootstrap
         if (pACL != nullptr) {
             HeapFree(GetProcessHeap(), 0, pACL);
         }
+        if (pLocalSystemSid != nullptr) {
+            HeapFree(GetProcessHeap(), 0, pLocalSystemSid);
+        }
         if (pTokenUser != nullptr) {
             HeapFree(GetProcessHeap(), 0, pTokenUser);
         }

src/core/Tools.cpp

@@ -39,23 +39,6 @@
 #include <time.h> // for nanosleep()
 #endif
 
-#include "config-keepassx.h"
-
-#if defined(HAVE_RLIMIT_CORE)
-#include <sys/resource.h>
-#endif
-
-#if defined(HAVE_PR_SET_DUMPABLE)
-#include <sys/prctl.h>
-#endif
-
-#ifdef HAVE_PT_DENY_ATTACH
-// clang-format off
-#include <sys/types.h>
-#include <sys/ptrace.h>
-// clang-format on
-#endif
-
 namespace Tools
 {
     QString humanReadableFileSize(qint64 bytes, quint32 precision)

src/sshagent/AgentSettingsWidget.cpp

@@ -26,6 +26,9 @@ AgentSettingsWidget::AgentSettingsWidget(QWidget* parent)
     , m_ui(new Ui::AgentSettingsWidget())
 {
     m_ui->setupUi(this);
+#ifndef Q_OS_WIN
+    m_ui->useOpenSSHCheckBox->setVisible(false);
+#endif
 }
 
 AgentSettingsWidget::~AgentSettingsWidget()
@@ -35,9 +38,15 @@ AgentSettingsWidget::~AgentSettingsWidget()
 void AgentSettingsWidget::loadSettings()
 {
     m_ui->enableSSHAgentCheckBox->setChecked(config()->get("SSHAgent", false).toBool());
+#ifdef Q_OS_WIN
+    m_ui->useOpenSSHCheckBox->setChecked(config()->get("SSHAgentOpenSSH", false).toBool());
+#endif
 }
 
 void AgentSettingsWidget::saveSettings()
 {
     config()->set("SSHAgent", m_ui->enableSSHAgentCheckBox->isChecked());
+#ifdef Q_OS_WIN
+    config()->set("SSHAgentOpenSSH", m_ui->useOpenSSHCheckBox->isChecked());
+#endif
 }

src/sshagent/AgentSettingsWidget.ui

@@ -30,6 +30,13 @@
      </property>
     </widget>
    </item>
+   <item>
+    <widget class="QCheckBox" name="useOpenSSHCheckBox">
+     <property name="text">
+      <string>Use OpenSSH for Windows instead of Pageant</string>
+     </property>
+    </widget>
+   </item>
    <item>
     <spacer name="verticalSpacer">
      <property name="orientation">

src/sshagent/SSHAgent.cpp

@@ -19,10 +19,10 @@
 #include "SSHAgent.h"
 #include "BinaryStream.h"
 #include "KeeAgentSettings.h"
-
-#ifndef Q_OS_WIN
+#include "core/Config.h"
 #include <QtNetwork>
-#else
+
+#ifdef Q_OS_WIN
 #include <windows.h>
 #endif
 
@@ -33,6 +33,8 @@ SSHAgent::SSHAgent(QObject* parent)
 {
 #ifndef Q_OS_WIN
     m_socketPath = QProcessEnvironment::systemEnvironment().value("SSH_AUTH_SOCK");
+#else
+    m_socketPath = "\\\\.\\pipe\\openssh-ssh-agent";
 #endif
 }
 
@@ -70,13 +72,22 @@ bool SSHAgent::isAgentRunning() const
 #ifndef Q_OS_WIN
     return !m_socketPath.isEmpty();
 #else
-    return (FindWindowA("Pageant", "Pageant") != nullptr);
+    if (!config()->get("SSHAgentOpenSSH").toBool()) {
+        return (FindWindowA("Pageant", "Pageant") != nullptr);
+    } else {
+        return WaitNamedPipe(m_socketPath.toLatin1().data(), 100);
+    }
 #endif
 }
 
 bool SSHAgent::sendMessage(const QByteArray& in, QByteArray& out)
 {
-#ifndef Q_OS_WIN
+#ifdef Q_OS_WIN
+    if (!config()->get("SSHAgentOpenSSH").toBool()) {
+        return sendMessagePageant(in, out);
+    }
+#endif
+
     QLocalSocket socket;
     BinaryStream stream(&socket);
 
@@ -97,7 +108,11 @@ bool SSHAgent::sendMessage(const QByteArray& in, QByteArray& out)
     socket.close();
 
     return true;
-#else
+}
+
+#ifdef Q_OS_WIN
+bool SSHAgent::sendMessagePageant(const QByteArray& in, QByteArray& out)
+{
     HWND hWnd = FindWindowA("Pageant", "Pageant");
 
     if (!hWnd) {
@@ -157,8 +172,8 @@ bool SSHAgent::sendMessage(const QByteArray& in, QByteArray& out)
     CloseHandle(handle);
 
     return (res > 0);
-#endif
 }
+#endif
 
 /**
  * Add the identity to the SSH agent.

src/sshagent/SSHAgent.h

@@ -62,12 +62,14 @@ public slots:
     ~SSHAgent();
 
     bool sendMessage(const QByteArray& in, QByteArray& out);
+#ifdef Q_OS_WIN
+    bool sendMessagePageant(const QByteArray& in, QByteArray& out);
+#endif
 
     static SSHAgent* m_instance;
 
-#ifndef Q_OS_WIN
     QString m_socketPath;
-#else
+#ifdef Q_OS_WIN
     const quint32 AGENT_MAX_MSGLEN = 8192;
     const quint32 AGENT_COPYDATA_ID = 0x804e50ba;
 #endif