Fixed bug #42560

Check open_basedir after the fallback to the system's temporary
directory in tempnam().

In order to preserve the current behavior of upload_tmp_dir
(do not check explicitly specified dir, but check fallback),
new flags are added to check open_basedir for explicit dir
and for fallback.

Closes GH-6526.

ext/standard/file.c

@@ -831,18 +831,14 @@ PHP_FUNCTION(tempnam)
 		Z_PARAM_PATH(prefix, prefix_len)
 	ZEND_PARSE_PARAMETERS_END();
 
-	if (php_check_open_basedir(dir)) {
-		RETURN_FALSE;
-	}
-
 	p = php_basename(prefix, prefix_len, NULL, 0);
 	if (ZSTR_LEN(p) > 64) {
 		ZSTR_VAL(p)[63] = '\0';
 	}
 
 	RETVAL_FALSE;
 
-	if ((fd = php_open_temporary_fd_ex(dir, ZSTR_VAL(p), &opened_path, 1)) >= 0) {
+	if ((fd = php_open_temporary_fd_ex(dir, ZSTR_VAL(p), &opened_path, PHP_TMP_FILE_OPEN_BASEDIR_CHECK_ALWAYS)) >= 0) {
 		close(fd);
 		RETVAL_STR(opened_path);
 	}

ext/standard/tests/file/bug42560.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Bug #42560 Empty directory argument to tempnam yields open_basedir problems
+--FILE--
+<?php
+$tmpdir = sys_get_temp_dir();
+ini_set('open_basedir', $tmpdir);
+$tempnam = tempnam('', 'test');
+var_dump($tempnam !== false);
+var_dump(file_exists($tempnam));
+
+if (file_exists($tempnam)) {
+    unlink($tempnam);
+}
+?>
+--EXPECT--
+bool(true)
+bool(true)

main/php_open_temporary_file.c

@@ -301,13 +301,19 @@ PHPAPI int php_open_temporary_fd_ex(const char *dir, const char *pfx, zend_strin
 def_tmp:
 		temp_dir = php_get_temporary_directory();
 
-		if (temp_dir && *temp_dir != '\0' && (!(flags & PHP_TMP_FILE_OPEN_BASEDIR_CHECK) || !php_check_open_basedir(temp_dir))) {
+		if (temp_dir &&
+		    *temp_dir != '\0' &&
+		    (!(flags & PHP_TMP_FILE_OPEN_BASEDIR_CHECK_ON_FALLBACK) || !php_check_open_basedir(temp_dir))) {
 			return php_do_open_temporary_file(temp_dir, pfx, opened_path_p);
 		} else {
 			return -1;
 		}
 	}
 
+	if ((flags & PHP_TMP_FILE_OPEN_BASEDIR_CHECK_ON_EXPLICIT_DIR) && php_check_open_basedir(dir)) {
+		return -1;
+	}
+
 	/* Try the directory given as parameter. */
 	fd = php_do_open_temporary_file(dir, pfx, opened_path_p);
 	if (fd == -1) {
@@ -322,7 +328,7 @@ PHPAPI int php_open_temporary_fd_ex(const char *dir, const char *pfx, zend_strin
 
 PHPAPI int php_open_temporary_fd(const char *dir, const char *pfx, zend_string **opened_path_p)
 {
-	return php_open_temporary_fd_ex(dir, pfx, opened_path_p, 0);
+	return php_open_temporary_fd_ex(dir, pfx, opened_path_p, PHP_TMP_FILE_DEFAULT);
 }
 
 PHPAPI FILE *php_open_temporary_file(const char *dir, const char *pfx, zend_string **opened_path_p)

main/php_open_temporary_file.h

@@ -19,8 +19,16 @@
 #ifndef PHP_OPEN_TEMPORARY_FILE_H
 #define PHP_OPEN_TEMPORARY_FILE_H
 
-#define PHP_TMP_FILE_OPEN_BASEDIR_CHECK (1<<0)
+#define PHP_TMP_FILE_DEFAULT 0
+#define PHP_TMP_FILE_OPEN_BASEDIR_CHECK_ON_FALLBACK (1<<0)
 #define PHP_TMP_FILE_SILENT (1<<1)
+#define PHP_TMP_FILE_OPEN_BASEDIR_CHECK_ON_EXPLICIT_DIR (1<<2)
+#define PHP_TMP_FILE_OPEN_BASEDIR_CHECK_ALWAYS \
+    (PHP_TMP_FILE_OPEN_BASEDIR_CHECK_ON_FALLBACK | PHP_TMP_FILE_OPEN_BASEDIR_CHECK_ON_EXPLICIT_DIR)
+
+/* for compatibility purpose */
+#define PHP_TMP_FILE_OPEN_BASEDIR_CHECK PHP_TMP_FILE_OPEN_BASEDIR_CHECK_ON_FALLBACK
+
 
 BEGIN_EXTERN_C()
 PHPAPI FILE *php_open_temporary_file(const char *dir, const char *pfx, zend_string **opened_path_p);

main/rfc1867.c

@@ -1009,7 +1009,7 @@ SAPI_API SAPI_POST_HANDLER_FUNC(rfc1867_post_handler) /* {{{ */
 				/* in non-debug mode we have no problem with 0-length files */
 				{
 #endif
-					fd = php_open_temporary_fd_ex(PG(upload_tmp_dir), "php", &temp_filename, 1);
+					fd = php_open_temporary_fd_ex(PG(upload_tmp_dir), "php", &temp_filename, PHP_TMP_FILE_OPEN_BASEDIR_CHECK_ON_FALLBACK);
 					upload_cnt--;
 					if (fd == -1) {
 						sapi_module.sapi_error(E_WARNING, "File upload error - unable to create a temporary file");

tests/security/open_basedir_tempnam.phpt

@@ -63,7 +63,7 @@ bool(false)
 Warning: tempnam(): open_basedir restriction in effect. File(./../.) is not within the allowed path(s): (.) in %s on line %d
 bool(false)
 
-Warning: tempnam(): open_basedir restriction in effect. File() is not within the allowed path(s): (.) in %s on line %d
+Warning: tempnam(): open_basedir restriction in effect. File(%s) is not within the allowed path(s): (.) in %s on line %d
 bool(false)
 string(%d) "%s"
 bool(true)