From 8ba10b8fbc020dc225d3b19d8f088f1351a3e304 Mon Sep 17 00:00:00 2001 From: "Christoph M. Becker" Date: Mon, 20 May 2019 15:59:54 +0200 Subject: [PATCH] Fix ASLR related invalid opline handler issues Opcache stores `opline->handler`s in shared memory. These pointers are invalid, if the main PHP DLL is loaded at another base address due to ASLR. We therefore store the address of `execute_ex` in the mmap base file, and check on startup whether it matches its current address. If not, we fall back on the file cache if enabled, and bail out otherwise. This still does not address cases where the opline handler is located inside of another DLL (e.g. for some profilers, debuggers), but there seems to be no general solution for now. --- ext/opcache/shared_alloc_win32.c | 39 ++++++++++++++++++++++++++------ 1 file changed, 32 insertions(+), 7 deletions(-) diff --git a/ext/opcache/shared_alloc_win32.c b/ext/opcache/shared_alloc_win32.c index 27f3d6cd13..2755f39486 100644 --- a/ext/opcache/shared_alloc_win32.c +++ b/ext/opcache/shared_alloc_win32.c @@ -22,6 +22,7 @@ #include "ZendAccelerator.h" #include "zend_shared_alloc.h" #include "zend_accelerator_util_funcs.h" +#include "zend_execute.h" #include "tsrm_win32.h" #include "win32/winutil.h" #include @@ -133,6 +134,8 @@ static int zend_shared_alloc_reattach(size_t requested_size, char **error_in) char *mmap_base_file = get_mmap_base_file(); FILE *fp = fopen(mmap_base_file, "r"); MEMORY_BASIC_INFORMATION info; + void *execute_ex_base; + int execute_ex_moved; if (!fp) { err = GetLastError(); @@ -148,6 +151,13 @@ static int zend_shared_alloc_reattach(size_t requested_size, char **error_in) fclose(fp); return ALLOC_FAILURE; } + if (!fscanf(fp, "%p", &execute_ex_base)) { + err = GetLastError(); + zend_win_error_message(ACCEL_LOG_FATAL, "Unable to read execute_ex base address", err); + *error_in="read execute_ex base"; + fclose(fp); + return ALLOC_FAILURE; + } fclose(fp); if (0 > win32_utime(mmap_base_file, NULL)) { @@ -155,8 +165,11 @@ static int zend_shared_alloc_reattach(size_t requested_size, char **error_in) zend_win_error_message(ACCEL_LOG_WARNING, mmap_base_file, err); } - /* Check if the requested address space is free */ - if (VirtualQuery(wanted_mapping_base, &info, sizeof(info)) == 0 || + execute_ex_moved = (void *)execute_ex != execute_ex_base; + + /* Check if execute_ex is at the same address and if the requested address space is free */ + if (execute_ex_moved || + VirtualQuery(wanted_mapping_base, &info, sizeof(info)) == 0 || info.State != MEM_FREE || info.RegionSize < requested_size) { #if ENABLE_FILE_CACHE_FALLBACK @@ -165,8 +178,13 @@ static int zend_shared_alloc_reattach(size_t requested_size, char **error_in) wanted_mb_save = (size_t)wanted_mapping_base; - err = ERROR_INVALID_ADDRESS; - zend_win_error_message(ACCEL_LOG_WARNING, "Base address marks unusable memory region (fall-back to file cache)", err); + if (execute_ex_moved) { + err = ERROR_INVALID_ADDRESS; + zend_win_error_message(ACCEL_LOG_WARNING, "Opcode handlers are unusable due to ASLR (fall-back to file cache)", err); + } else { + err = ERROR_INVALID_ADDRESS; + zend_win_error_message(ACCEL_LOG_WARNING, "Base address marks unusable memory region (fall-back to file cache)", err); + } pre_size = ZEND_ALIGNED_SIZE(sizeof(zend_smm_shared_globals)) + ZEND_ALIGNED_SIZE(sizeof(zend_shared_segment)) + ZEND_ALIGNED_SIZE(sizeof(void *)) + ZEND_ALIGNED_SIZE(sizeof(int)); /* Map only part of SHM to have access opcache shared globals */ @@ -181,10 +199,15 @@ static int zend_shared_alloc_reattach(size_t requested_size, char **error_in) return ALLOC_FALLBACK; } #endif - err = ERROR_INVALID_ADDRESS; - zend_win_error_message(ACCEL_LOG_FATAL, "Base address marks unusable memory region. Please setup opcache.file_cache and opcache.file_cache_fallback directives for more convenient Opcache usage", err); + if (execute_ex_moved) { + err = ERROR_INVALID_ADDRESS; + zend_win_error_message(ACCEL_LOG_FATAL, "Opcode handlers are unusable due to ASLR. Please setup opcache.file_cache and opcache.file_cache_fallback directives for more convenient Opcache usage", err); + } else { + err = ERROR_INVALID_ADDRESS; + zend_win_error_message(ACCEL_LOG_FATAL, "Base address marks unusable memory region. Please setup opcache.file_cache and opcache.file_cache_fallback directives for more convenient Opcache usage", err); + } return ALLOC_FAILURE; - } + } mapping_base = MapViewOfFileEx(memfile, FILE_MAP_ALL_ACCESS, 0, 0, 0, wanted_mapping_base); @@ -315,6 +338,7 @@ static int create_segments(size_t requested_size, zend_shared_segment ***shared_ return ALLOC_FAILURE; } else { char *mmap_base_file = get_mmap_base_file(); + void *execute_ex_base = (void *)execute_ex; FILE *fp = fopen(mmap_base_file, "w"); if (!fp) { err = GetLastError(); @@ -324,6 +348,7 @@ static int create_segments(size_t requested_size, zend_shared_segment ***shared_ return ALLOC_FAILURE; } fprintf(fp, "%p\n", mapping_base); + fprintf(fp, "%p\n", execute_ex_base); fclose(fp); } -- 2.40.0