/* * The PCI Library -- Win32 helper functions * * Copyright (c) 2023 Pali Rohár * * Can be freely distributed and used under the terms of the GNU GPL v2+ * * SPDX-License-Identifier: GPL-2.0-or-later */ #include #include /* for sprintf() */ #include "win32-helpers.h" /* Unfortunately i586-mingw32msvc toolchain does not provide this constant. */ #ifndef PROCESS_QUERY_LIMITED_INFORMATION #define PROCESS_QUERY_LIMITED_INFORMATION 0x1000 #endif /* Unfortunately some toolchains do not provide this constant. */ #ifndef SE_IMPERSONATE_NAME #define SE_IMPERSONATE_NAME TEXT("SeImpersonatePrivilege") #endif /* Unfortunately some toolchains do not provide these constants. */ #ifndef SE_DACL_AUTO_INHERIT_REQ #define SE_DACL_AUTO_INHERIT_REQ 0x0100 #endif #ifndef SE_SACL_AUTO_INHERIT_REQ #define SE_SACL_AUTO_INHERIT_REQ 0x0200 #endif #ifndef SE_DACL_AUTO_INHERITED #define SE_DACL_AUTO_INHERITED 0x0400 #endif #ifndef SE_SACL_AUTO_INHERITED #define SE_SACL_AUTO_INHERITED 0x0800 #endif /* * These psapi functions are available in kernel32.dll library with K32 prefix * on Windows 7 and higher systems. On older Windows systems these functions are * available in psapi.dll libary without K32 prefix. So resolve pointers to * these functions dynamically at runtime from the available system library. * Function GetProcessImageFileNameW() is not available on Windows 2000 and * older systems. */ typedef BOOL (WINAPI *EnumProcessesProt)(DWORD *lpidProcess, DWORD cb, DWORD *cbNeeded); typedef DWORD (WINAPI *GetProcessImageFileNameWProt)(HANDLE hProcess, LPWSTR lpImageFileName, DWORD nSize); typedef DWORD (WINAPI *GetModuleFileNameExWProt)(HANDLE hProcess, HMODULE hModule, LPWSTR lpImageFileName, DWORD nSize); /* * These aclapi function is available in advapi.dll library on Windows 2000 * and higher systems. */ typedef BOOL (WINAPI *SetSecurityDescriptorControlProt)(PSECURITY_DESCRIPTOR pSecurityDescriptor, SECURITY_DESCRIPTOR_CONTROL ControlBitsOfInterest, SECURITY_DESCRIPTOR_CONTROL ControlBitsToSet); /* * This errhandlingapi function is available in kernel32.dll library on * Windows 7 and higher systems. */ typedef BOOL (WINAPI *SetThreadErrorModeProt)(DWORD dwNewMode, LPDWORD lpOldMode); static DWORD format_message_from_system(DWORD win32_error_id, DWORD lang_id, LPSTR buffer, DWORD size) { return FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, win32_error_id, lang_id, buffer, size, NULL); } const char * win32_strerror(DWORD win32_error_id) { /* * Use static buffer which is large enough. * Hopefully no Win32 API error message string is longer than 4 kB. */ static char buffer[4096]; DWORD len; /* * If it is possible show error messages in US English language. * International Windows editions do not have to provide error * messages in English language, so fallback to the language * which system provides (neutral). */ len = format_message_from_system(win32_error_id, MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US), buffer, sizeof(buffer)); if (!len) len = format_message_from_system(win32_error_id, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), buffer, sizeof(buffer)); /* FormatMessage() automatically appends ".\r\n" to the error message. */ if (len && buffer[len-1] == '\n') buffer[--len] = '\0'; if (len && buffer[len-1] == '\r') buffer[--len] = '\0'; if (len && buffer[len-1] == '.') buffer[--len] = '\0'; if (!len) sprintf(buffer, "Unknown Win32 error %lu", win32_error_id); return buffer; } BOOL win32_is_non_nt_system(void) { OSVERSIONINFOA version; version.dwOSVersionInfoSize = sizeof(version); return GetVersionExA(&version) && version.dwPlatformId < VER_PLATFORM_WIN32_NT; } BOOL win32_is_32bit_on_64bit_system(void) { BOOL (WINAPI *MyIsWow64Process)(HANDLE, PBOOL); HMODULE kernel32; BOOL is_wow64; /* * Check for 64-bit system via IsWow64Process() function exported * from 32-bit kernel32.dll library available on the 64-bit systems. * Resolve pointer to this function at runtime as this code path is * primary running on 32-bit systems where are not available 64-bit * functions. */ kernel32 = GetModuleHandle(TEXT("kernel32.dll")); if (!kernel32) return FALSE; MyIsWow64Process = (void *)GetProcAddress(kernel32, "IsWow64Process"); if (!MyIsWow64Process) return FALSE; if (!MyIsWow64Process(GetCurrentProcess(), &is_wow64)) return FALSE; return is_wow64; } BOOL win32_is_32bit_on_win8_64bit_system(void) { #ifdef _WIN64 return FALSE; #else OSVERSIONINFOA version; /* Check for Windows 8 (NT 6.2). */ version.dwOSVersionInfoSize = sizeof(version); if (!GetVersionExA(&version) || version.dwPlatformId != VER_PLATFORM_WIN32_NT || version.dwMajorVersion < 6 || (version.dwMajorVersion == 6 && version.dwMinorVersion < 2)) return FALSE; return win32_is_32bit_on_64bit_system(); #endif } /* * Change error mode of the current thread. If it is not possible then change * error mode of the whole process. Always returns previous error mode. */ UINT win32_change_error_mode(UINT new_mode) { SetThreadErrorModeProt MySetThreadErrorMode = NULL; HMODULE kernel32; DWORD old_mode; /* * Function SetThreadErrorMode() was introduced in Windows 7, so use * GetProcAddress() for compatibility with older systems. */ kernel32 = GetModuleHandle(TEXT("kernel32.dll")); if (kernel32) MySetThreadErrorMode = (SetThreadErrorModeProt)(LPVOID)GetProcAddress(kernel32, "SetThreadErrorMode"); if (MySetThreadErrorMode && MySetThreadErrorMode(new_mode, &old_mode)) return old_mode; /* * Fallback to function SetErrorMode() which modifies error mode of the * whole process and returns old mode. */ return SetErrorMode(new_mode); } /* * Check if the current thread has particular privilege in current active access * token. Case when it not possible to determinate it (e.g. current thread does * not have permission to open its own current active access token) is evaluated * as thread does not have that privilege. */ BOOL win32_have_privilege(LUID luid_privilege) { PRIVILEGE_SET priv; HANDLE token; BOOL ret; /* * If the current thread does not have active access token then thread * uses primary process access token for all permission checks. */ if (!OpenThreadToken(GetCurrentThread(), TOKEN_QUERY, TRUE, &token) && (GetLastError() != ERROR_NO_TOKEN || !OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &token))) return FALSE; priv.PrivilegeCount = 1; priv.Control = PRIVILEGE_SET_ALL_NECESSARY; priv.Privilege[0].Luid = luid_privilege; priv.Privilege[0].Attributes = SE_PRIVILEGE_ENABLED; if (!PrivilegeCheck(token, &priv, &ret)) return FALSE; return ret; } /* * Enable or disable particular privilege in specified access token. * * Note that it is not possible to disable privilege in access token with * SE_PRIVILEGE_ENABLED_BY_DEFAULT attribute. This function does not check * this case and incorrectly returns no error even when disabling failed. * Rationale for this decision: Simplification of this function as WinAPI * call AdjustTokenPrivileges() does not signal error in this case too. */ static BOOL set_privilege(HANDLE token, LUID luid_privilege, BOOL enable) { TOKEN_PRIVILEGES token_privileges; token_privileges.PrivilegeCount = 1; token_privileges.Privileges[0].Luid = luid_privilege; token_privileges.Privileges[0].Attributes = enable ? SE_PRIVILEGE_ENABLED : 0; /* * WinAPI function AdjustTokenPrivileges() success also when not all * privileges were enabled. It is always required to check for failure * via GetLastError() call. AdjustTokenPrivileges() always sets error * also when it success, as opposite to other WinAPI functions. */ if (!AdjustTokenPrivileges(token, FALSE, &token_privileges, sizeof(token_privileges), NULL, NULL) || GetLastError() != ERROR_SUCCESS) return FALSE; return TRUE; } /* * Change access token for the current thread to new specified access token. * Previously active access token is stored in old_token variable and can be * used for reverting to this access token. It is set to NULL if the current * thread previously used primary process access token. */ BOOL win32_change_token(HANDLE new_token, HANDLE *old_token) { HANDLE token; if (!OpenThreadToken(GetCurrentThread(), TOKEN_IMPERSONATE, TRUE, &token)) { if (GetLastError() != ERROR_NO_TOKEN) return FALSE; token = NULL; } if (!ImpersonateLoggedOnUser(new_token)) { if (token) CloseHandle(token); return FALSE; } *old_token = token; return TRUE; } /* * Change access token for the current thread to the primary process access * token. This function fails also when the current thread already uses primary * process access token. */ static BOOL change_token_to_primary(HANDLE *old_token) { HANDLE token; if (!OpenThreadToken(GetCurrentThread(), TOKEN_IMPERSONATE, TRUE, &token)) return FALSE; RevertToSelf(); *old_token = token; return TRUE; } /* * Revert to the specified access token for the current thread. When access * token is specified as NULL then revert to the primary process access token. * Use to revert after win32_change_token() or change_token_to_primary() call. */ VOID win32_revert_to_token(HANDLE token) { /* * If SetThreadToken() call fails then there is no option to revert to * the specified previous thread access token. So in this case revert to * the primary process access token. */ if (!token || !SetThreadToken(NULL, token)) RevertToSelf(); if (token) CloseHandle(token); } /* * Enable particular privilege for the current thread. And set method how to * revert this privilege (if to revert whole token or only privilege). */ BOOL win32_enable_privilege(LUID luid_privilege, HANDLE *revert_token, BOOL *revert_only_privilege) { HANDLE thread_token; HANDLE new_token; if (OpenThreadToken(GetCurrentThread(), TOKEN_ADJUST_PRIVILEGES, TRUE, &thread_token)) { if (set_privilege(thread_token, luid_privilege, TRUE)) { /* * Indicate that correct revert method is just to * disable privilege in access token. */ if (revert_token && revert_only_privilege) { *revert_token = thread_token; *revert_only_privilege = TRUE; } else { CloseHandle(thread_token); } return TRUE; } CloseHandle(thread_token); /* * If enabling privilege failed then try to enable it via * primary process access token. */ } /* * If the current thread has already active thread access token then * open it with just impersonate right as it would be used only for * future revert. */ if (revert_token && revert_only_privilege) { if (!OpenThreadToken(GetCurrentThread(), TOKEN_IMPERSONATE, TRUE, &thread_token)) { if (GetLastError() != ERROR_NO_TOKEN) return FALSE; thread_token = NULL; } /* * If current thread has no access token (and uses primary * process access token) or it does not have permission to * adjust privileges or it does not have specified privilege * then create a copy of the primary process access token, * assign it for the current thread (= impersonate self) * and then try adjusting privilege again. */ if (!ImpersonateSelf(SecurityImpersonation)) { if (thread_token) CloseHandle(thread_token); return FALSE; } } if (!OpenThreadToken(GetCurrentThread(), TOKEN_ADJUST_PRIVILEGES, TRUE, &new_token)) { /* thread_token is set only when we were asked for revert method. */ if (revert_token && revert_only_privilege) win32_revert_to_token(thread_token); return FALSE; } if (!set_privilege(new_token, luid_privilege, TRUE)) { CloseHandle(new_token); /* thread_token is set only when we were asked for revert method. */ if (revert_token && revert_only_privilege) win32_revert_to_token(thread_token); return FALSE; } /* * Indicate that correct revert method is to change to the previous * access token. Either to the primary process access token or to the * previous thread access token. */ if (revert_token && revert_only_privilege) { *revert_token = thread_token; *revert_only_privilege = FALSE; } return TRUE; } /* * Revert particular privilege for the current thread was previously enabled by * win32_enable_privilege() call. Either disable privilege in specified access token * or revert to previous access token. */ VOID win32_revert_privilege(LUID luid_privilege, HANDLE revert_token, BOOL revert_only_privilege) { if (revert_only_privilege) { set_privilege(revert_token, luid_privilege, FALSE); CloseHandle(revert_token); } else { win32_revert_to_token(revert_token); } } /* * Return owner of the access token used by the current thread. Buffer for * returned owner needs to be released by LocalFree() call. */ static TOKEN_OWNER * get_current_token_owner(VOID) { HANDLE token; DWORD length; TOKEN_OWNER *owner; /* * If the current thread does not have active access token then thread * uses primary process access token for all permission checks. */ if (!OpenThreadToken(GetCurrentThread(), TOKEN_QUERY, TRUE, &token) && (GetLastError() != ERROR_NO_TOKEN || !OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &token))) return NULL; if (!GetTokenInformation(token, TokenOwner, NULL, 0, &length) && GetLastError() != ERROR_INSUFFICIENT_BUFFER) { CloseHandle(token); return NULL; } retry: owner = (TOKEN_OWNER *)LocalAlloc(LPTR, length); if (!owner) { CloseHandle(token); return NULL; } if (!GetTokenInformation(token, TokenOwner, owner, length, &length)) { /* * Length of token owner (SID) buffer between two get calls may * changes (e.g. by another thread of process), so retry. */ if (GetLastError() == ERROR_INSUFFICIENT_BUFFER) { LocalFree(owner); goto retry; } LocalFree(owner); CloseHandle(token); return NULL; } CloseHandle(token); return owner; } /* * Create a new security descriptor in absolute form from relative form. * Newly created security descriptor in absolute form is stored in linear buffer. */ static PSECURITY_DESCRIPTOR create_relsd_from_abssd(PSECURITY_DESCRIPTOR rel_security_descriptor) { PBYTE abs_security_descriptor_buffer; DWORD abs_security_descriptor_size=0, abs_dacl_size=0, abs_sacl_size=0, abs_owner_size=0, abs_primary_group_size=0; if (!MakeAbsoluteSD(rel_security_descriptor, NULL, &abs_security_descriptor_size, NULL, &abs_dacl_size, NULL, &abs_sacl_size, NULL, &abs_owner_size, NULL, &abs_primary_group_size) && GetLastError() != ERROR_INSUFFICIENT_BUFFER) return NULL; abs_security_descriptor_buffer = (PBYTE)LocalAlloc(LPTR, abs_security_descriptor_size+abs_dacl_size+abs_sacl_size+abs_owner_size+abs_primary_group_size); if (!abs_security_descriptor_buffer) return NULL; if (!MakeAbsoluteSD(rel_security_descriptor, (PSECURITY_DESCRIPTOR)abs_security_descriptor_buffer, &abs_security_descriptor_size, (PACL)(abs_security_descriptor_buffer+abs_security_descriptor_size), &abs_dacl_size, (PACL)(abs_security_descriptor_buffer+abs_security_descriptor_size+abs_dacl_size), &abs_sacl_size, (PSID)(abs_security_descriptor_buffer+abs_security_descriptor_size+abs_dacl_size+abs_sacl_size), &abs_owner_size, (PSID)(abs_security_descriptor_buffer+abs_security_descriptor_size+abs_dacl_size+abs_sacl_size+abs_owner_size), &abs_primary_group_size)) return NULL; return (PSECURITY_DESCRIPTOR)abs_security_descriptor_buffer; } /* * Prepare security descriptor obtained by GetKernelObjectSecurity() so it can be * passed to SetKernelObjectSecurity() as identity operation. It modifies control * flags of security descriptor, which is needed for Windows 2000 and new. */ static BOOL prepare_security_descriptor_for_set_operation(PSECURITY_DESCRIPTOR security_descriptor) { SetSecurityDescriptorControlProt MySetSecurityDescriptorControl; SECURITY_DESCRIPTOR_CONTROL bits_mask; SECURITY_DESCRIPTOR_CONTROL bits_set; SECURITY_DESCRIPTOR_CONTROL control; OSVERSIONINFO version; HMODULE advapi32; DWORD revision; /* * SE_DACL_AUTO_INHERITED and SE_SACL_AUTO_INHERITED are flags introduced in * Windows 2000 to control client-side automatic inheritance (client - user * process - is responsible for propagating inherited ACEs to subobjects). * To prevent applications which do not understand client-side automatic * inheritance (applications created prior Windows 2000 or which use low * level API like SetKernelObjectSecurity()) to unintentionally set those * SE_DACL_AUTO_INHERITED and SE_SACL_AUTO_INHERITED control flags when * coping them from other security descriptor. * * As we are not modifying existing ACEs, we are compatible with Windows 2000 * client-side automatic inheritance model and therefore prepare security * descriptor for SetKernelObjectSecurity() to not clear existing automatic * inheritance control flags. * * Control flags SE_DACL_AUTO_INHERITED and SE_SACL_AUTO_INHERITED are set * into security object only when they are set together with set-only flags * SE_DACL_AUTO_INHERIT_REQ and SE_SACL_AUTO_INHERIT_REQ. Those flags are * never received by GetKernelObjectSecurity() and are just commands for * SetKernelObjectSecurity() how to interpret SE_DACL_AUTO_INHERITED and * SE_SACL_AUTO_INHERITED flags. * * Function symbol SetSecurityDescriptorControl is not available in the * older versions of advapi32.dll library, so resolve it at runtime. */ version.dwOSVersionInfoSize = sizeof(version); if (!GetVersionEx(&version) || version.dwPlatformId != VER_PLATFORM_WIN32_NT || version.dwMajorVersion < 5) return TRUE; if (!GetSecurityDescriptorControl(security_descriptor, &control, &revision)) return FALSE; bits_mask = 0; bits_set = 0; if (control & SE_DACL_AUTO_INHERITED) { bits_mask |= SE_DACL_AUTO_INHERIT_REQ; bits_set |= SE_DACL_AUTO_INHERIT_REQ; } if (control & SE_SACL_AUTO_INHERITED) { bits_mask |= SE_SACL_AUTO_INHERIT_REQ; bits_set |= SE_SACL_AUTO_INHERIT_REQ; } if (!bits_mask) return TRUE; advapi32 = GetModuleHandle(TEXT("advapi32.dll")); if (!advapi32) return FALSE; MySetSecurityDescriptorControl = (SetSecurityDescriptorControlProt)(LPVOID)GetProcAddress(advapi32, "SetSecurityDescriptorControl"); if (!MySetSecurityDescriptorControl) return FALSE; if (!MySetSecurityDescriptorControl(security_descriptor, bits_mask, bits_set)) return FALSE; return TRUE; } /* * Grant particular permissions in the primary access token of the specified * process for the owner of current thread token and set old DACL of the * process access token for reverting permissions. Security descriptor is * just memory buffer for old DACL. */ static BOOL grant_process_token_dacl_permissions(HANDLE process, DWORD permissions, HANDLE *token, PSECURITY_DESCRIPTOR *old_security_descriptor) { TOKEN_OWNER *owner; PACL old_dacl; BOOL old_dacl_present; BOOL old_dacl_defaulted; PACL new_dacl; WORD new_dacl_size; PSECURITY_DESCRIPTOR new_security_descriptor; DWORD length; owner = get_current_token_owner(); if (!owner) return FALSE; /* * READ_CONTROL is required for GetSecurityInfo(DACL_SECURITY_INFORMATION) * and WRITE_DAC is required for SetSecurityInfo(DACL_SECURITY_INFORMATION). */ if (!OpenProcessToken(process, READ_CONTROL | WRITE_DAC, token)) { LocalFree(owner); return FALSE; } if (!GetKernelObjectSecurity(*token, DACL_SECURITY_INFORMATION, NULL, 0, &length) && GetLastError() != ERROR_INSUFFICIENT_BUFFER) { LocalFree(owner); CloseHandle(*token); return FALSE; } retry: *old_security_descriptor = (PSECURITY_DESCRIPTOR)LocalAlloc(LPTR, length); if (!*old_security_descriptor) { LocalFree(owner); CloseHandle(*token); return FALSE; } if (!GetKernelObjectSecurity(*token, DACL_SECURITY_INFORMATION, *old_security_descriptor, length, &length)) { /* * Length of the security descriptor between two get calls * may changes (e.g. by another thread of process), so retry. */ if (GetLastError() == ERROR_INSUFFICIENT_BUFFER) { LocalFree(*old_security_descriptor); goto retry; } LocalFree(*old_security_descriptor); LocalFree(owner); CloseHandle(*token); return FALSE; } if (!prepare_security_descriptor_for_set_operation(*old_security_descriptor)) { LocalFree(*old_security_descriptor); LocalFree(owner); CloseHandle(*token); return FALSE; } /* Retrieve the current DACL from security descriptor including present and defaulted properties. */ if (!GetSecurityDescriptorDacl(*old_security_descriptor, &old_dacl_present, &old_dacl, &old_dacl_defaulted)) { LocalFree(*old_security_descriptor); LocalFree(owner); CloseHandle(*token); return FALSE; } /* * If DACL is not present then system grants full access to everyone. It this * case do not modify DACL as it just adds one ACL allow rule for us, which * automatically disallow access to anybody else which had access before. */ if (!old_dacl_present || !old_dacl) { LocalFree(*old_security_descriptor); LocalFree(owner); *old_security_descriptor = NULL; return TRUE; } /* Create new DACL which would be copy of the current old one. */ new_dacl_size = old_dacl->AclSize + sizeof(ACCESS_ALLOWED_ACE) + GetLengthSid(owner->Owner) - sizeof(DWORD); new_dacl = (PACL)LocalAlloc(LPTR, new_dacl_size); if (!new_dacl) { LocalFree(*old_security_descriptor); LocalFree(owner); CloseHandle(*token); return FALSE; } /* * Initialize new DACL structure to the same format as was the old one. * Set new explicit access for the owner of the current thread access * token with non-inherited granting access to specified permissions. * This permission is added in the first ACE, so has the highest priority. */ if (!InitializeAcl(new_dacl, new_dacl_size, old_dacl->AclRevision) || !AddAccessAllowedAce(new_dacl, ACL_REVISION2, permissions, owner->Owner)) { LocalFree(new_dacl); LocalFree(*old_security_descriptor); LocalFree(owner); CloseHandle(*token); return FALSE; } /* * Now (after setting our new permissions) append all ACE entries from the * old DACL to the new DACL, which preserve all other existing permissions. */ if (old_dacl->AceCount > 0) { WORD ace_index; LPVOID ace; for (ace_index = 0; ace_index < old_dacl->AceCount; ace_index++) { if (!GetAce(old_dacl, ace_index, &ace) || !AddAce(new_dacl, old_dacl->AclRevision, MAXDWORD, ace, ((PACE_HEADER)ace)->AceSize)) { LocalFree(new_dacl); LocalFree(*old_security_descriptor); LocalFree(owner); CloseHandle(*token); return FALSE; } } } /* * Create copy of the old security descriptor, so we can modify its DACL. * Function SetSecurityDescriptorDacl() works only with security descriptors * in absolute format. So use our helper function create_relsd_from_abssd() * for converting security descriptor from relative format (which is returned * by GetKernelObjectSecurity() function) to the absolute format. */ new_security_descriptor = create_relsd_from_abssd(*old_security_descriptor); if (!new_security_descriptor) { LocalFree(new_dacl); LocalFree(*old_security_descriptor); LocalFree(owner); CloseHandle(*token); return FALSE; } /* * In the new security descriptor replace old DACL by the new DACL (which has * new permissions) and then set this new security descriptor to the token, * so token would have new access permissions. */ if (!SetSecurityDescriptorDacl(new_security_descriptor, TRUE, new_dacl, FALSE) || !SetKernelObjectSecurity(*token, DACL_SECURITY_INFORMATION, new_security_descriptor)) { LocalFree(new_security_descriptor); LocalFree(new_dacl); LocalFree(*old_security_descriptor); LocalFree(owner); CloseHandle(*token); return FALSE; } LocalFree(new_security_descriptor); LocalFree(new_dacl); LocalFree(owner); return TRUE; } /* * Revert particular granted permissions in specified access token done by * grant_process_token_dacl_permissions() call. */ static VOID revert_token_dacl_permissions(HANDLE token, PSECURITY_DESCRIPTOR old_security_descriptor) { SetKernelObjectSecurity(token, DACL_SECURITY_INFORMATION, old_security_descriptor); LocalFree(old_security_descriptor); CloseHandle(token); } /* * Open process handle specified by the process id with the query right and * optionally also with vm read right. */ static HANDLE open_process_for_query(DWORD pid, BOOL with_vm_read) { BOOL revert_only_privilege; LUID luid_debug_privilege; OSVERSIONINFO version; DWORD process_right; HANDLE revert_token; HANDLE process; /* * Some processes on Windows Vista and higher systems can be opened only * with PROCESS_QUERY_LIMITED_INFORMATION right. This right is enough * for accessing primary process token. But this right is not supported * on older pre-Vista systems. When the current thread on these older * systems does not have Debug privilege then OpenProcess() fails with * ERROR_ACCESS_DENIED. If the current thread has Debug privilege then * OpenProcess() success and returns handle to requested process. * Problem is that this handle does not have PROCESS_QUERY_INFORMATION * right and so cannot be used for accessing primary process token * on those older systems. Moreover it has zero rights and therefore * such handle is fully useless. So never try to use open process with * PROCESS_QUERY_LIMITED_INFORMATION right on older systems than * Windows Vista (NT 6.0). */ version.dwOSVersionInfoSize = sizeof(version); if (GetVersionEx(&version) && version.dwPlatformId == VER_PLATFORM_WIN32_NT && version.dwMajorVersion >= 6) process_right = PROCESS_QUERY_LIMITED_INFORMATION; else process_right = PROCESS_QUERY_INFORMATION; if (with_vm_read) process_right |= PROCESS_VM_READ; process = OpenProcess(process_right, FALSE, pid); if (process) return process; /* * It is possible to open only processes to which owner of the current * thread access token has permissions. For opening other processing it * is required to have Debug privilege enabled. By default local * administrators have this privilege, but it is disabled. So try to * enable it and then try to open process again. */ if (!LookupPrivilegeValue(NULL, SE_DEBUG_NAME, &luid_debug_privilege)) return NULL; if (!win32_enable_privilege(luid_debug_privilege, &revert_token, &revert_only_privilege)) return NULL; process = OpenProcess(process_right, FALSE, pid); win32_revert_privilege(luid_debug_privilege, revert_token, revert_only_privilege); return process; } /* * Check if process image path name (wide string) matches exe file name * (7-bit ASCII string). Do case-insensitive string comparison. Process * image path name can be in any namespace format (DOS, Win32, UNC, ...). */ static BOOL check_process_name(LPCWSTR path, DWORD path_length, LPCSTR exe_file) { DWORD exe_file_length; WCHAR c1; UCHAR c2; DWORD i; exe_file_length = 0; while (exe_file[exe_file_length] != '\0') exe_file_length++; /* Path must have backslash before exe file name. */ if (exe_file_length >= path_length || path[path_length-exe_file_length-1] != L'\\') return FALSE; for (i = 0; i < exe_file_length; i++) { c1 = path[path_length-exe_file_length+i]; c2 = exe_file[i]; /* * Input string for comparison is 7-bit ASCII and file name part * of path must not contain backslash as it is path separator. */ if (c1 >= 0x80 || c2 >= 0x80 || c1 == L'\\') return FALSE; if (c1 >= L'a' && c1 <= L'z') c1 -= L'a' - L'A'; if (c2 >= 'a' && c2 <= 'z') c2 -= 'a' - 'A'; if (c1 != c2) return FALSE; } return TRUE; } /* Open process handle with the query right specified by process exe file. */ HANDLE win32_find_and_open_process_for_query(LPCSTR exe_file) { GetProcessImageFileNameWProt MyGetProcessImageFileNameW; GetModuleFileNameExWProt MyGetModuleFileNameExW; EnumProcessesProt MyEnumProcesses; HMODULE kernel32, psapi; UINT prev_error_mode; DWORD partial_retry; BOOL found_process; DWORD size, length; DWORD *processes; HANDLE process; LPWSTR path; DWORD error; DWORD count; DWORD i; psapi = NULL; kernel32 = GetModuleHandle(TEXT("kernel32.dll")); if (!kernel32) return NULL; /* * On Windows 7 and higher systems these functions are available in * kernel32.dll library with K32 prefix. */ MyGetModuleFileNameExW = NULL; MyGetProcessImageFileNameW = (GetProcessImageFileNameWProt)(LPVOID)GetProcAddress(kernel32, "K32GetProcessImageFileNameW"); MyEnumProcesses = (EnumProcessesProt)(LPVOID)GetProcAddress(kernel32, "K32EnumProcesses"); if (!MyGetProcessImageFileNameW || !MyEnumProcesses) { /* * On older NT-based systems these functions are available in * psapi.dll library without K32 prefix. */ prev_error_mode = win32_change_error_mode(SEM_FAILCRITICALERRORS); psapi = LoadLibrary(TEXT("psapi.dll")); win32_change_error_mode(prev_error_mode); if (!psapi) return NULL; /* * Function GetProcessImageFileNameW() is available in * Windows XP and higher systems. On older versions is * available function GetModuleFileNameExW(). */ MyGetProcessImageFileNameW = (GetProcessImageFileNameWProt)(LPVOID)GetProcAddress(psapi, "GetProcessImageFileNameW"); MyGetModuleFileNameExW = (GetModuleFileNameExWProt)(LPVOID)GetProcAddress(psapi, "GetModuleFileNameExW"); MyEnumProcesses = (EnumProcessesProt)(LPVOID)GetProcAddress(psapi, "EnumProcesses"); if ((!MyGetProcessImageFileNameW && !MyGetModuleFileNameExW) || !MyEnumProcesses) { FreeLibrary(psapi); return NULL; } } /* Make initial buffer size for 1024 processes. */ size = 1024 * sizeof(*processes); retry: processes = (DWORD *)LocalAlloc(LPTR, size); if (!processes) { if (psapi) FreeLibrary(psapi); return NULL; } if (!MyEnumProcesses(processes, size, &length)) { LocalFree(processes); if (psapi) FreeLibrary(psapi); return NULL; } else if (size == length) { /* * There is no indication given when the buffer is too small to * store all process identifiers. Therefore if returned length * is same as buffer size there can be more processes. Call * again with larger buffer. */ LocalFree(processes); size *= 2; goto retry; } process = NULL; count = length / sizeof(*processes); for (i = 0; i < count; i++) { /* Skip System Idle Process. */ if (processes[i] == 0) continue; /* * Function GetModuleFileNameExW() requires additional * PROCESS_VM_READ right as opposite to function * GetProcessImageFileNameW() which does not need it. */ process = open_process_for_query(processes[i], MyGetProcessImageFileNameW ? FALSE : TRUE); if (!process) continue; /* * Set initial buffer size to 256 (wide) characters. * Final path length on the modern NT-based systems can be also larger. */ size = 256; found_process = FALSE; partial_retry = 0; retry_path: path = (LPWSTR)LocalAlloc(LPTR, size * sizeof(*path)); if (!path) goto end_path; if (MyGetProcessImageFileNameW) length = MyGetProcessImageFileNameW(process, path, size); else length = MyGetModuleFileNameExW(process, NULL, path, size); error = GetLastError(); /* * GetModuleFileNameEx() returns zero and signal error ERROR_PARTIAL_COPY * when remote process is in the middle of updating its module table. * Sleep 10 ms and try again, max 10 attempts. */ if (!MyGetProcessImageFileNameW) { if (length == 0 && error == ERROR_PARTIAL_COPY && partial_retry++ < 10) { Sleep(10); goto retry_path; } partial_retry = 0; } /* * When buffer is too small then function GetModuleFileNameEx() returns * its size argument on older systems (Windows XP) or its size minus * argument one on new systems (Windows 10) without signalling any error. * Function GetProcessImageFileNameW() on the other hand returns zero * value and signals error ERROR_INSUFFICIENT_BUFFER. So in all these * cases call function again with larger buffer. */ if (MyGetProcessImageFileNameW && length == 0 && error != ERROR_INSUFFICIENT_BUFFER) goto end_path; if ((MyGetProcessImageFileNameW && length == 0) || (!MyGetProcessImageFileNameW && (length == size || length == size-1))) { LocalFree(path); size *= 2; goto retry_path; } if (length && check_process_name(path, length, exe_file)) found_process = TRUE; end_path: if (path) { LocalFree(path); path = NULL; } if (found_process) break; CloseHandle(process); process = NULL; } LocalFree(processes); if (psapi) FreeLibrary(psapi); return process; } /* * Try to open primary access token of the particular process with specified * rights. Before opening access token try to adjust DACL permissions of the * primary process access token, so following open does not fail on error * related to no open permissions. Revert DACL permissions after open attempt. * As following steps are not atomic, try to execute them more times in case * of possible race conditions caused by other threads or processes. */ static HANDLE try_grant_permissions_and_open_process_token(HANDLE process, DWORD rights) { PSECURITY_DESCRIPTOR old_security_descriptor; HANDLE grant_token; HANDLE token; DWORD retry; DWORD error; /* * This code is not atomic. Between grant and open calls can other * thread or process change or revert permissions. So try to execute * it more times. */ for (retry = 0; retry < 10; retry++) { if (!grant_process_token_dacl_permissions(process, rights, &grant_token, &old_security_descriptor)) return NULL; if (!OpenProcessToken(process, rights, &token)) { token = NULL; error = GetLastError(); } if (old_security_descriptor) revert_token_dacl_permissions(grant_token, old_security_descriptor); if (token) return token; else if (error != ERROR_ACCESS_DENIED) return NULL; } return NULL; } /* * Open primary access token of particular process handle with specified rights. * If permissions for specified rights are missing then try to grant them. */ HANDLE win32_open_process_token_with_rights(HANDLE process, DWORD rights) { HANDLE old_token; HANDLE token; /* First try to open primary access token of process handle directly. */ if (OpenProcessToken(process, rights, &token)) return token; /* * If opening failed then it means that owner of the current thread * access token does not have permission for it. Try it again with * primary process access token. */ if (change_token_to_primary(&old_token)) { if (!OpenProcessToken(process, rights, &token)) token = NULL; win32_revert_to_token(old_token); if (token) return token; } /* * If opening is still failing then try to grant specified permissions * for the current thread and try to open it again. */ token = try_grant_permissions_and_open_process_token(process, rights); if (token) return token; /* * And if it is still failing then try it again with granting * permissions for the primary process token of the current process. */ if (change_token_to_primary(&old_token)) { token = try_grant_permissions_and_open_process_token(process, rights); win32_revert_to_token(old_token); if (token) return token; } /* * TODO: Sorry, no other option for now... * It could be possible to use Take Ownership Name privilege to * temporary change token owner of specified process to the owner of * the current thread token, grant permissions for current thread in * that process token, change ownership back to original one, open * that process token and revert granted permissions. But this is * not implemented yet. */ return NULL; } /* * Call supplied function with its argument and if it fails with * ERROR_PRIVILEGE_NOT_HELD then try to enable Tcb privilege and * call function with its argument again. */ BOOL win32_call_func_with_tcb_privilege(BOOL (*function)(LPVOID), LPVOID argument) { LUID luid_tcb_privilege; LUID luid_impersonate_privilege; HANDLE revert_token_tcb_privilege; BOOL revert_only_tcb_privilege; HANDLE revert_token_impersonate_privilege; BOOL revert_only_impersonate_privilege; BOOL impersonate_privilege_enabled; BOOL revert_to_old_token; HANDLE old_token; HANDLE lsass_process; HANDLE lsass_token; BOOL ret; impersonate_privilege_enabled = FALSE; revert_to_old_token = FALSE; lsass_token = NULL; old_token = NULL; /* Call supplied function. */ ret = function(argument); if (ret || GetLastError() != ERROR_PRIVILEGE_NOT_HELD) goto ret; /* * If function call failed with ERROR_PRIVILEGE_NOT_HELD * error then it means that the current thread token does not have * Tcb privilege enabled. Try to enable it. */ if (!LookupPrivilegeValue(NULL, SE_TCB_NAME, &luid_tcb_privilege)) goto err_privilege_not_held; /* * If the current thread has already Tcb privilege enabled then there * is some additional unhanded restriction. */ if (win32_have_privilege(luid_tcb_privilege)) goto err_privilege_not_held; /* Try to enable Tcb privilege and try function call again. */ if (win32_enable_privilege(luid_tcb_privilege, &revert_token_tcb_privilege, &revert_only_tcb_privilege)) { ret = function(argument); win32_revert_privilege(luid_tcb_privilege, revert_token_tcb_privilege, revert_only_tcb_privilege); goto ret; } /* * If enabling of Tcb privilege failed then it means that current thread * does not have this privilege. But current process may have it. So try it * again with primary process access token. */ /* * If system supports Impersonate privilege (Windows 2000 SP4 or higher) then * all future actions in this function require this Impersonate privilege. * So try to enable it in case it is currently disabled. */ if (LookupPrivilegeValue(NULL, SE_IMPERSONATE_NAME, &luid_impersonate_privilege) && !win32_have_privilege(luid_impersonate_privilege)) { /* * If current thread does not have Impersonate privilege enabled * then first try to enable it just for the current thread. If * it is not possible to enable it just for the current thread * then try it to enable globally for whole process (which * affects all process threads). Both actions will be reverted * at the end of this function. */ if (win32_enable_privilege(luid_impersonate_privilege, &revert_token_impersonate_privilege, &revert_only_impersonate_privilege)) { impersonate_privilege_enabled = TRUE; } else if (win32_enable_privilege(luid_impersonate_privilege, NULL, NULL)) { impersonate_privilege_enabled = TRUE; revert_token_impersonate_privilege = NULL; revert_only_impersonate_privilege = TRUE; } else { goto err_privilege_not_held; } /* * Now when Impersonate privilege is enabled, try to enable Tcb * privilege again. Enabling other privileges for the current * thread requires Impersonate privilege, so enabling Tcb again * could now pass. */ if (win32_enable_privilege(luid_tcb_privilege, &revert_token_tcb_privilege, &revert_only_tcb_privilege)) { ret = function(argument); win32_revert_privilege(luid_tcb_privilege, revert_token_tcb_privilege, revert_only_tcb_privilege); goto ret; } } /* * If enabling Tcb privilege failed then it means that the current * thread access token does not have this privilege or does not * have permission to adjust privileges. * * Try to use more privileged token from Local Security Authority * Subsystem Service process (lsass.exe) which has Tcb privilege. * Retrieving this more privileged token is possible for local * administrators (unless it was disabled by local administrators). */ lsass_process = win32_find_and_open_process_for_query("lsass.exe"); if (!lsass_process) goto err_privilege_not_held; /* * Open primary lsass.exe process access token with query and duplicate * rights. Just these two rights are required for impersonating other * primary process token (impersonate right is really not required!). */ lsass_token = win32_open_process_token_with_rights(lsass_process, TOKEN_QUERY | TOKEN_DUPLICATE); CloseHandle(lsass_process); if (!lsass_token) goto err_privilege_not_held; /* * After successful open of the primary lsass.exe process access token, * assign its copy for the current thread. */ if (!win32_change_token(lsass_token, &old_token)) goto err_privilege_not_held; revert_to_old_token = TRUE; ret = function(argument); if (ret || GetLastError() != ERROR_PRIVILEGE_NOT_HELD) goto ret; /* * Now current thread is not using primary process token anymore * but is using custom access token. There is no need to revert * enabled Tcb privilege as the whole custom access token would * be reverted. So there is no need to setup revert method for * enabling privilege. */ if (win32_have_privilege(luid_tcb_privilege) || !win32_enable_privilege(luid_tcb_privilege, NULL, NULL)) goto err_privilege_not_held; ret = function(argument); goto ret; err_privilege_not_held: SetLastError(ERROR_PRIVILEGE_NOT_HELD); ret = FALSE; goto ret; ret: if (revert_to_old_token) win32_revert_to_token(old_token); if (impersonate_privilege_enabled) win32_revert_privilege(luid_impersonate_privilege, revert_token_impersonate_privilege, revert_only_impersonate_privilege); if (lsass_token) CloseHandle(lsass_token); return ret; }