Fix handling of restricted processes for Windows Vista (mainly),

by explicitly adding back the user to the DACL of the new process.
This fixes the failure case when executing as the Administrator
user, which had no permissions left at all after we dropped the
Administrators group.

Dave Page with some modifications from me

Author: mhagander

src/bin/initdb/initdb.c

@@ -42,7 +42,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  * Portions taken from FreeBSD.
  *
- * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.153 2008/02/20 22:46:24 tgl Exp $
+ * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.154 2008/02/29 15:31:33 mha Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2329,7 +2329,26 @@ CreateRestrictedProcess(char *cmd, PROCESS_INFORMATION * processInfo)
 		return 0;
 	}
 
-	return CreateProcessAsUser(restrictedToken, NULL, cmd, NULL, NULL, TRUE, 0, NULL, NULL, &si, processInfo);
+	if (!CreateProcessAsUser(restrictedToken,
+						NULL,
+						cmd,
+						NULL,
+						NULL,
+						TRUE,
+						CREATE_SUSPENDED,
+						NULL,
+						NULL,
+						&si,
+						processInfo))
+
+	{
+		fprintf(stderr, "CreateProcessAsUser failed: %lu\n", GetLastError());
+		return 0;
+	}
+
+	AddUserToDacl(processInfo->hProcess);
+
+	return ResumeThread(processInfo->hThread);
 }
 #endif
 

src/bin/pg_ctl/pg_ctl.c

@@ -4,7 +4,7 @@
  *
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/bin/pg_ctl/pg_ctl.c,v 1.94 2008/02/20 22:46:24 tgl Exp $
+ * $PostgreSQL: pgsql/src/bin/pg_ctl/pg_ctl.c,v 1.95 2008/02/29 15:31:33 mha Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1469,6 +1469,8 @@ CreateRestrictedProcess(char *cmd, PROCESS_INFORMATION * processInfo)
 		}
 	}
 
+    AddUserToDacl(processInfo->hProcess);
+    
 	CloseHandle(restrictedToken);
 
 	ResumeThread(processInfo->hThread);

src/include/port.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/port.h,v 1.117 2008/02/18 14:51:48 petere Exp $
+ * $PostgreSQL: pgsql/src/include/port.h,v 1.118 2008/02/29 15:31:33 mha Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -79,6 +79,12 @@ extern int	find_my_exec(const char *argv0, char *retpath);
 extern int find_other_exec(const char *argv0, const char *target,
 				const char *versionstr, char *retpath);
 
+/* Windows security token manipulation (in exec.c) */
+#ifdef WIN32
+extern BOOL AddUserToDacl(HANDLE hProcess);
+#endif
+
+
 #if defined(WIN32) || defined(__CYGWIN__)
 #define EXE ".exe"
 #else

src/port/exec.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/port/exec.c,v 1.57 2008/01/01 19:46:00 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/port/exec.c,v 1.58 2008/02/29 15:31:33 mha Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -55,6 +55,9 @@ static int	validate_exec(const char *path);
 static int	resolve_symlinks(char *path);
 static char *pipe_read_line(char *cmd, char *line, int maxsize);
 
+#ifdef WIN32
+static BOOL GetUserSid(PSID * ppSidUser, HANDLE hToken);
+#endif
 
 /*
  * validate_exec -- validate "path" as an executable file
@@ -657,3 +660,217 @@ set_pglocale_pgservice(const char *argv0, const char *app)
 		putenv(strdup(env_path));
 	}
 }
+
+#ifdef WIN32
+
+/*
+ * AddUserToDacl(HANDLE hProcess)
+ *
+ * This function adds the current user account to the default DACL
+ * which gets attached to the restricted token used when we create
+ * a restricted process.
+ *
+ * This is required because of some security changes in Windows
+ * that appeared in patches to XP/2K3 and in Vista/2008.
+ *
+ * On these machines, the Administrator account is not included in
+ * the default DACL - you just get Administrators + System. For
+ * regular users you get User + System. Because we strip Administrators
+ * when we create the restricted token, we are left with only System
+ * in the DACL which leads to access denied errors for later CreatePipe()
+ * and CreateProcess() calls when running as Administrator.
+ *
+ * This function fixes this problem by modifying the DACL of the
+ * specified process and explicitly re-adding the current user account.
+ * This is still secure because the Administrator account inherits it's
+ * privileges from the Administrators group - it doesn't have any of
+ * it's own.
+ */
+BOOL
+AddUserToDacl(HANDLE hProcess)
+{
+	int			i;
+	ACL_SIZE_INFORMATION asi;
+	ACCESS_ALLOWED_ACE *pace;
+	DWORD		dwNewAclSize;
+	DWORD		dwSize = 0;
+	DWORD		dwTokenInfoLength = 0;
+	DWORD		dwResult = 0;
+	HANDLE		hToken = NULL;
+	PACL		pacl = NULL;
+	PSID		psidUser = NULL;
+	TOKEN_DEFAULT_DACL tddNew;
+	TOKEN_DEFAULT_DACL *ptdd = NULL;
+	TOKEN_INFORMATION_CLASS tic = TokenDefaultDacl;
+	BOOL		ret = FALSE;
+
+	/* Get the token for the process */
+	if (!OpenProcessToken(hProcess, TOKEN_QUERY | TOKEN_ADJUST_DEFAULT, &hToken))
+	{
+		log_error("could not open process token: %ui", GetLastError());
+		goto cleanup;
+	}
+
+	/* Figure out the buffer size for the DACL info */
+	if (!GetTokenInformation(hToken, tic, (LPVOID) NULL, dwTokenInfoLength, &dwSize))
+	{
+		if (GetLastError() == ERROR_INSUFFICIENT_BUFFER)
+		{
+			ptdd = (TOKEN_DEFAULT_DACL *) LocalAlloc(LPTR, dwSize);
+			if (ptdd == NULL)
+			{
+				log_error("could not allocate %i bytes of memory", dwSize);
+				goto cleanup;
+			}
+
+			if (!GetTokenInformation(hToken, tic, (LPVOID) ptdd, dwSize, &dwSize))
+			{
+				log_error("could not get token information: %ui", GetLastError());
+				goto cleanup;
+			}
+		}
+		else
+		{
+			log_error("could not get token information buffer size: %ui", GetLastError());
+			goto cleanup;
+		}
+	}
+
+	/* Get the ACL info */
+	if (!GetAclInformation(ptdd->DefaultDacl, (LPVOID) & asi,
+						   (DWORD) sizeof(ACL_SIZE_INFORMATION),
+						   AclSizeInformation))
+	{
+		log_error("could not get ACL information: %ui", GetLastError());
+		goto cleanup;
+	}
+
+	/* Get the SID for the current user. We need to add this to the ACL. */
+	if (!GetUserSid(&psidUser, hToken))
+	{
+		log_error("could not get user SID: %ui", GetLastError());
+		goto cleanup;
+	}
+
+	/* Figure out the size of the new ACL */
+	dwNewAclSize = asi.AclBytesInUse + sizeof(ACCESS_ALLOWED_ACE) + GetLengthSid(psidUser) - sizeof(DWORD);
+
+	/* Allocate the ACL buffer & initialize it */
+	pacl = (PACL) LocalAlloc(LPTR, dwNewAclSize);
+	if (pacl == NULL)
+	{
+		log_error("could not allocate %i bytes of memory", dwNewAclSize);
+		goto cleanup;
+	}
+
+	if (!InitializeAcl(pacl, dwNewAclSize, ACL_REVISION))
+	{
+		log_error("could not initialize ACL: %ui", GetLastError());
+		goto cleanup;
+	}
+
+	/* Loop through the existing ACEs, and build the new ACL */
+	for (i = 0; i < (int) asi.AceCount; i++)
+	{
+		if (!GetAce(ptdd->DefaultDacl, i, (LPVOID *) & pace))
+		{
+			log_error("could not get ACE: %ui", GetLastError());
+			goto cleanup;
+		}
+
+		if (!AddAce(pacl, ACL_REVISION, MAXDWORD, pace, ((PACE_HEADER) pace)->AceSize))
+		{
+			log_error("could not add ACE: %ui", GetLastError());
+			goto cleanup;
+		}
+	}
+
+	/* Add the new ACE for the current user */
+	if (!AddAccessAllowedAce(pacl, ACL_REVISION, GENERIC_ALL, psidUser))
+	{
+		log_error("could not add access allowed ACE: %ui", GetLastError());
+		goto cleanup;
+	}
+
+	/* Set the new DACL in the token */
+	tddNew.DefaultDacl = pacl;
+
+	if (!SetTokenInformation(hToken, tic, (LPVOID) & tddNew, dwNewAclSize))
+	{
+		log_error("could not set token information: %ui", GetLastError());
+		goto cleanup;
+	}
+
+	ret = TRUE;
+
+cleanup:
+	if (psidUser)
+		FreeSid(psidUser);
+
+	if (pacl)
+		LocalFree((HLOCAL) pacl);
+
+	if (ptdd)
+		LocalFree((HLOCAL) ptdd);
+
+	if (hToken)
+		CloseHandle(hToken);
+
+	return ret;
+}
+
+/*
+ * GetUserSid*PSID *ppSidUser, HANDLE hToken)
+ *
+ * Get the SID for the current user
+ */
+static BOOL
+GetUserSid(PSID * ppSidUser, HANDLE hToken)
+{
+	DWORD		dwLength;
+	DWORD		cbName = 250;
+	DWORD		cbDomainName = 250;
+	PTOKEN_USER pTokenUser = NULL;
+
+
+	if (!GetTokenInformation(hToken,
+							 TokenUser,
+							 pTokenUser,
+							 0,
+							 &dwLength))
+	{
+		if (GetLastError() == ERROR_INSUFFICIENT_BUFFER)
+		{
+			pTokenUser = (PTOKEN_USER) HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, dwLength);
+
+			if (pTokenUser == NULL)
+			{
+				log_error("could not allocate %ui bytes of memory", dwLength);
+				return FALSE;
+			}
+		}
+		else
+		{
+			log_error("could not get token information buffer size: %ui", GetLastError());
+			return FALSE;
+		}
+	}
+
+	if (!GetTokenInformation(hToken,
+							 TokenUser,
+							 pTokenUser,
+							 dwLength,
+							 &dwLength))
+	{
+		HeapFree(GetProcessHeap(), 0, pTokenUser);
+		pTokenUser = NULL;
+
+		log_error("could not get token information: %ui", GetLastError());
+		return FALSE;
+	}
+
+	*ppSidUser = pTokenUser->User.Sid;
+	return TRUE;
+}
+
+#endif