Fix memory corruption and support WinPE

contrib/win32/openssh/README.txt

@@ -30,8 +30,7 @@ Before building OpenSSH for Windows, install the following:
    same install / v143 toolset automatically.
 
 2. Git for Windows.
-   The build script expects git.exe to be on PATH (it will add
-   "%ProgramFiles%\Git\cmd" to the machine PATH if missing).
+   The build script expects git.exe to be on PATH.
 
 3. vcpkg (one-time bootstrap).
    Dependencies (LibreSSL, libfido2, zlib, libcbor) are managed via a

contrib/win32/openssh/sshd-auth.vcxproj

@@ -1,6 +1,20 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="paths.targets" />
+  <!-- sshd-auth is a privsep helper spawned by sshd as a different user and has
+       no desktop/window-station access. user32's DllMain binds to the process
+       window station and fails with STATUS_DLL_INIT_FAILED in restricted
+       environments (e.g. WinPE). Two mitigations: (1) add delayimp.lib and
+       delay-load user32 so its DLL is only loaded when a user32 API is
+       actually called, and (2) keep user32.lib (needed for the delay-load
+       thunks). sshd-auth only transitively references ShowWindow /
+       GetWindowPlacement from console.c's ConRestoreViewRect_NoPtyHack
+       helper, which sshd-auth does not execute, so in practice user32 is
+       never loaded. The ItemDefinitionGroup with /DELAYLOAD is placed after
+       Microsoft.Cpp.props (where the Link item type becomes defined). -->
+  <PropertyGroup>
+    <AdditionalDependentLibs>$(AdditionalDependentLibs);delayimp.lib</AdditionalDependentLibs>
+  </PropertyGroup>
   <ItemGroup Label="ProjectConfigurations">
     <ProjectConfiguration Include="Debug|ARM">
       <Configuration>Debug</Configuration>
@@ -112,6 +126,11 @@
     <VcpkgEnableManifest>true</VcpkgEnableManifest>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ItemDefinitionGroup>
+    <Link>
+      <AdditionalOptions>/DELAYLOAD:user32.dll %(AdditionalOptions)</AdditionalOptions>
+    </Link>
+  </ItemDefinitionGroup>
   <ImportGroup Label="ExtensionSettings">
   </ImportGroup>
   <ImportGroup Label="Shared">

contrib/win32/win32compat/win32_usertoken_utils.c

@@ -94,6 +94,24 @@ EnablePrivilege(const char *privName, int enabled)
 	return;
 }
 
+static BOOL
+is_domain_joined_machine(void)
+{
+	BOOL result = FALSE;
+	LPWSTR name = NULL;
+	NETSETUP_JOIN_STATUS s = NetSetupUnknownStatus;
+	DWORD api_res = NetGetJoinInformation(NULL, &name, &s);
+	if (api_res == NERR_Success) {
+		result = s == NetSetupDomainName;
+		NetApiBufferFree(name);
+		name = NULL;
+	} else {
+		debug("%s: NetGetJoinInformation() failed. Error %d.", __FUNCTION__, api_res);
+	}
+	debug("%s: NetGetJoinInformation(). Join result %d", __FUNCTION__, result);
+	return result;
+}
+
 HANDLE
 generate_s4u_user_token(wchar_t* user_cpn, int impersonation) {
 	HANDLE lsa_handle = NULL, token = NULL;
@@ -112,7 +130,8 @@ generate_s4u_user_token(wchar_t* user_cpn, int impersonation) {
 	 * so only the only two formats are a NetBiosDomain\SamAccountName which is
 	 * a domain account or just SamAccountName in which is a local account */
 	BOOL domain_user = wcschr(user_cpn, L'\\') != NULL;
-
+	BOOL use_kerberos = domain_user && is_domain_joined_machine();
+
 	/* initialize connection to local security provider */
 	if (impersonation) {
 
@@ -132,11 +151,11 @@ generate_s4u_user_token(wchar_t* user_cpn, int impersonation) {
 			goto done;
 	}
 
-	InitLsaString(&auth_package_name, (domain_user) ? MICROSOFT_KERBEROS_NAME_A : MSV1_0_PACKAGE_NAME);
+	InitLsaString(&auth_package_name, use_kerberos ? MICROSOFT_KERBEROS_NAME_A : MSV1_0_PACKAGE_NAME);
 	if (ret = LsaLookupAuthenticationPackage(lsa_handle, &auth_package_name, &auth_package_id) != STATUS_SUCCESS)
 		goto done;
 
-	if (domain_user) {
+	if (use_kerberos) {
 
 		/* lookup the user principal name for the account */
 		WCHAR domain_upn[MAX_UPN_LEN + 1];
@@ -168,6 +187,11 @@ generate_s4u_user_token(wchar_t* user_cpn, int impersonation) {
 	}
 	else {
 
+		/* if a domain prefix slipped through (non-domain-joined host. e.g. winpe is backed with such domain), 
+		  point past it without mutating the caller's buffer */
+		wchar_t *backslash = wcschr(user_cpn, L'\\');
+		if (backslash != NULL)
+			user_cpn = backslash + 1;
 		MSV1_0_S4U_LOGON *s4u_logon;
 		logon_info_size = sizeof(MSV1_0_S4U_LOGON);
 
@@ -432,7 +456,7 @@ load_user_profile(HANDLE user_token, char* user)
 	EnablePrivilege("SeBackupPrivilege", 1);
 	EnablePrivilege("SeRestorePrivilege", 1);
 	if (LoadUserProfileW(user_token, &profileInfo) == FALSE) {
-		debug3("%s: LoadUserProfileW() failed for user %S with error %d.", __FUNCTION__, GetLastError());
+		debug3("%s: LoadUserProfileW() failed for user %S with error %d.", __FUNCTION__, user_name, GetLastError());
 	}
 	EnablePrivilege("SeBackupPrivilege", 0);
 	EnablePrivilege("SeRestorePrivilege", 0);