Add system ID entropy API

The `zend_system_id` is a (true global) system ID that fingerprints a process state. When extensions add engine hooks during MINIT/startup, entropy is added the system ID for each hook. This allows extensions to identify that changes have been made to the engine since the last PHP process restart.

Closes GH-5871

1 files changed, 91 insertions, 0 deletions

diff --git a/Zend/zend_system_id.c b/Zend/zend_system_id.c
new file mode 100644
index 0000000000..93bca57b0c
--- /dev/null
+++ b/Zend/zend_system_id.c
@@ -0,0 +1,91 @@
+/*
+   +----------------------------------------------------------------------+
+   | Copyright (c) The PHP Group                                          |
+   +----------------------------------------------------------------------+
+   | This source file is subject to version 3.01 of the PHP license,      |
+   | that is bundled with this package in the file LICENSE, and is        |
+   | available through the world-wide-web at the following url:           |
+   | http://www.php.net/license/3_01.txt                                  |
+   | If you did not receive a copy of the PHP license and are unable to   |
+   | obtain it through the world-wide-web, please send a note to          |
+   | license@php.net so we can mail you a copy immediately.               |
+   +----------------------------------------------------------------------+
+   | Authors: Sammy Kaye Powers <sammyk@php.net>                          |
+   |          Dmitry Stogov <dmitry@php.net>                              |
+   +----------------------------------------------------------------------+
+ */
+
+#include "php.h"
+#include "zend_system_id.h"
+#include "zend_extensions.h"
+#include "ext/standard/md5.h"
+#include "ext/hash/php_hash.h"
+
+ZEND_API char zend_system_id[32];
+
+static PHP_MD5_CTX context;
+static int finalized = 0;
+
+ZEND_API ZEND_RESULT_CODE zend_add_system_entropy(const char *module_name, const char *hook_name, const void *data, size_t size)
+{
+	if (finalized == 0) {
+		PHP_MD5Update(&context, module_name, strlen(module_name));
+		PHP_MD5Update(&context, hook_name, strlen(hook_name));
+		if (size) {
+			PHP_MD5Update(&context, data, size);
+		}
+		return SUCCESS;
+	}
+	return FAILURE;
+}
+
+#define ZEND_BIN_ID "BIN_" ZEND_TOSTR(SIZEOF_INT) ZEND_TOSTR(SIZEOF_LONG) ZEND_TOSTR(SIZEOF_SIZE_T) ZEND_TOSTR(SIZEOF_ZEND_LONG) ZEND_TOSTR(ZEND_MM_ALIGNMENT)
+
+void zend_startup_system_id(void)
+{
+	PHP_MD5Init(&context);
+	PHP_MD5Update(&context, PHP_VERSION, sizeof(PHP_VERSION)-1);
+	PHP_MD5Update(&context, ZEND_EXTENSION_BUILD_ID, sizeof(ZEND_EXTENSION_BUILD_ID)-1);
+	PHP_MD5Update(&context, ZEND_BIN_ID, sizeof(ZEND_BIN_ID)-1);
+	if (strstr(PHP_VERSION, "-dev") != 0) {
+		/* Development versions may be changed from build to build */
+		PHP_MD5Update(&context, __DATE__, sizeof(__DATE__)-1);
+		PHP_MD5Update(&context, __TIME__, sizeof(__TIME__)-1);
+	}
+	zend_system_id[0] = '\0';
+}
+
+#define ZEND_HOOK_AST_PROCESS      (1 << 0)
+#define ZEND_HOOK_COMPILE_FILE     (1 << 1)
+#define ZEND_HOOK_EXECUTE_EX       (1 << 2)
+#define ZEND_HOOK_EXECUTE_INTERNAL (1 << 3)
+
+void zend_finalize_system_id(void)
+{
+	unsigned char digest[16];
+	zend_uchar hooks = 0;
+
+	if (zend_ast_process) {
+		hooks |= ZEND_HOOK_AST_PROCESS;
+	}
+	if (zend_compile_file != compile_file) {
+		hooks |= ZEND_HOOK_COMPILE_FILE;
+	}
+	if (zend_execute_ex != execute_ex) {
+		hooks |= ZEND_HOOK_EXECUTE_EX;
+	}
+	if (zend_execute_internal) {
+		hooks |= ZEND_HOOK_EXECUTE_INTERNAL;
+	}
+	PHP_MD5Update(&context, &hooks, sizeof hooks);
+
+	for (int16_t i = 0; i < 256; i++) {
+		if (zend_get_user_opcode_handler((zend_uchar) i) != NULL) {
+			PHP_MD5Update(&context, &i, sizeof i);
+		}
+	}
+
+	PHP_MD5Final(digest, &context);
+	php_hash_bin2hex(zend_system_id, digest, sizeof digest);
+	finalized = 1;
+}