Run pg_upgrade and pg_resetxlog with restricted token on Windows

As with initdb these programs need to run with a restricted token, and
if they don't pg_upgrade will fail when run as a user with Adminstrator
privileges.

Backpatch to all live branches. On the development branch the code is
reorganized so that the restricted token code is now in a single
location. On the stable bramches a less invasive change is made by
simply copying the relevant code to pg_upgrade.c and pg_resetxlog.c.

Patches and bug report from Muhammad Asif Naeem, reviewed by Michael
Paquier, slightly edited by me.

Author: adunstan

contrib/pg_upgrade/pg_upgrade.c

@@ -50,6 +50,11 @@ static void copy_clog_xlog_xid(void);
 static void set_frozenxids(void);
 static void setup(char *argv0, bool live_check);
 static void cleanup(void);
+static void	get_restricted_token(const char *progname);
+
+#ifdef WIN32
+static int	CreateRestrictedProcess(char *cmd, PROCESS_INFORMATION *processInfo, const char *progname);
+#endif
 
 ClusterInfo old_cluster,
 			new_cluster;
@@ -67,6 +72,9 @@ char	   *output_files[] = {
 	NULL
 };
 
+#ifdef WIN32
+static char *restrict_env;
+#endif
 
 int
 main(int argc, char **argv)
@@ -78,6 +86,8 @@ main(int argc, char **argv)
 
 	parseCommandLine(argc, argv);
 
+	get_restricted_token(os_info.progname);
+
 	adjust_data_dir(&old_cluster);
 	adjust_data_dir(&new_cluster);
 
@@ -170,6 +180,162 @@ main(int argc, char **argv)
 	return 0;
 }
 
+#ifdef WIN32
+typedef BOOL(WINAPI * __CreateRestrictedToken) (HANDLE, DWORD, DWORD, PSID_AND_ATTRIBUTES, DWORD, PLUID_AND_ATTRIBUTES, DWORD, PSID_AND_ATTRIBUTES, PHANDLE);
+
+/* Windows API define missing from some versions of MingW headers */
+#ifndef  DISABLE_MAX_PRIVILEGE
+#define DISABLE_MAX_PRIVILEGE	0x1
+#endif
+
+/*
+* Create a restricted token and execute the specified process with it.
+*
+* Returns 0 on failure, non-zero on success, same as CreateProcess().
+*
+* On NT4, or any other system not containing the required functions, will
+* NOT execute anything.
+*/
+static int
+CreateRestrictedProcess(char *cmd, PROCESS_INFORMATION *processInfo, const char *progname)
+{
+	BOOL		b;
+	STARTUPINFO si;
+	HANDLE		origToken;
+	HANDLE		restrictedToken;
+	SID_IDENTIFIER_AUTHORITY NtAuthority = { SECURITY_NT_AUTHORITY };
+	SID_AND_ATTRIBUTES dropSids[2];
+	__CreateRestrictedToken _CreateRestrictedToken = NULL;
+	HANDLE		Advapi32Handle;
+
+	ZeroMemory(&si, sizeof(si));
+	si.cb = sizeof(si);
+
+	Advapi32Handle = LoadLibrary("ADVAPI32.DLL");
+	if (Advapi32Handle != NULL)
+	{
+		_CreateRestrictedToken = (__CreateRestrictedToken)GetProcAddress(Advapi32Handle, "CreateRestrictedToken");
+	}
+
+	if (_CreateRestrictedToken == NULL)
+	{
+		fprintf(stderr, _("%s: WARNING: cannot create restricted tokens on this platform\n"), progname);
+		if (Advapi32Handle != NULL)
+			FreeLibrary(Advapi32Handle);
+		return 0;
+	}
+
+	/* Open the current token to use as a base for the restricted one */
+	if (!OpenProcessToken(GetCurrentProcess(), TOKEN_ALL_ACCESS, &origToken))
+	{
+		fprintf(stderr, _("%s: could not open process token: error code %lu\n"), progname, GetLastError());
+		return 0;
+	}
+
+	/* Allocate list of SIDs to remove */
+	ZeroMemory(&dropSids, sizeof(dropSids));
+	if (!AllocateAndInitializeSid(&NtAuthority, 2,
+		SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS, 0, 0, 0, 0, 0,
+		0, &dropSids[0].Sid) ||
+		!AllocateAndInitializeSid(&NtAuthority, 2,
+		SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_POWER_USERS, 0, 0, 0, 0, 0,
+		0, &dropSids[1].Sid))
+	{
+		fprintf(stderr, _("%s: could not to allocate SIDs: error code %lu\n"), progname, GetLastError());
+		return 0;
+	}
+
+	b = _CreateRestrictedToken(origToken,
+						DISABLE_MAX_PRIVILEGE,
+						sizeof(dropSids) / sizeof(dropSids[0]),
+						dropSids,
+						0, NULL,
+						0, NULL,
+						&restrictedToken);
+
+	FreeSid(dropSids[1].Sid);
+	FreeSid(dropSids[0].Sid);
+	CloseHandle(origToken);
+	FreeLibrary(Advapi32Handle);
+
+	if (!b)
+	{
+		fprintf(stderr, _("%s: could not create restricted token: error code %lu\n"), progname, GetLastError());
+		return 0;
+	}
+
+#ifndef __CYGWIN__
+	AddUserToTokenDacl(restrictedToken);
+#endif
+
+	if (!CreateProcessAsUser(restrictedToken,
+							NULL,
+							cmd,
+							NULL,
+							NULL,
+							TRUE,
+							CREATE_SUSPENDED,
+							NULL,
+							NULL,
+							&si,
+							processInfo))
+
+	{
+		fprintf(stderr, _("%s: could not start process for command \"%s\": error code %lu\n"), progname, cmd, GetLastError());
+		return 0;
+	}
+
+	return ResumeThread(processInfo->hThread);
+}
+#endif
+
+void
+get_restricted_token(const char *progname)
+{
+#ifdef WIN32
+
+	/*
+	* Before we execute another program, make sure that we are running with a
+	* restricted token. If not, re-execute ourselves with one.
+	*/
+
+	if ((restrict_env = getenv("PG_RESTRICT_EXEC")) == NULL
+		|| strcmp(restrict_env, "1") != 0)
+	{
+		PROCESS_INFORMATION pi;
+		char	   *cmdline;
+
+		ZeroMemory(&pi, sizeof(pi));
+
+		cmdline = pg_strdup(GetCommandLine());
+
+		putenv("PG_RESTRICT_EXEC=1");
+
+		if (!CreateRestrictedProcess(cmdline, &pi, progname))
+		{
+			fprintf(stderr, _("%s: could not re-execute with restricted token: error code %lu\n"), progname, GetLastError());
+		}
+		else
+		{
+			/*
+			* Successfully re-execed. Now wait for child process to capture
+			* exitcode.
+			*/
+			DWORD		x;
+
+			CloseHandle(pi.hThread);
+			WaitForSingleObject(pi.hProcess, INFINITE);
+
+			if (!GetExitCodeProcess(pi.hProcess, &x))
+			{
+				fprintf(stderr, _("%s: could not get exit code from subprocess: error code %lu\n"), progname, GetLastError());
+				exit(1);
+			}
+			exit(x);
+		}
+	}
+#endif
+}
 
 static void
 setup(char *argv0, bool live_check)