libsandbox: initial support for wrapping *at functions #174233

URL: http://bugs.gentoo.org/174233
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Reported-by: Zhixu Liu <zhixu.liu@gmail.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/libsandbox/wrapper-funcs/openat.c b/libsandbox/wrapper-funcs/openat.c
new file mode 100644
index 0000000..ba97a1f
--- /dev/null
+++ b/libsandbox/wrapper-funcs/openat.c
@@ -0,0 +1,47 @@
+/*
+ * openat() wrapper.
+ *
+ * Copyright 1999-2008 Gentoo Foundation
+ * Licensed under the GPL-2
+ *
+ *  Partly Copyright (C) 1998-9 Pancrazio `Ezio' de Mauro <p@demauro.net>,
+ *  as some of the InstallWatch code was used.
+ */
+
+#define WRAPPER_ARGS int dirfd, const char *pathname, int flags, ...
+extern int EXTERN_NAME(WRAPPER_ARGS);
+static int (*WRAPPER_TRUE_NAME)(WRAPPER_ARGS) = NULL;
+
+/* Eventually, there is a third parameter: it's mode_t mode */
+int WRAPPER_NAME(WRAPPER_ARGS)
+{
+	va_list ap;
+	int mode = 0;
+	int result = -1;
+	int old_errno = errno;
+	struct stat st;
+
+	if (flags & O_CREAT) {
+		va_start(ap, flags);
+		mode = va_arg(ap, int);
+		va_end(ap);
+	} else {
+		/* XXX: If we're not trying to create, fail normally if
+		 *      file does not stat */
+		if (-1 == stat(pathname, &st)) {
+			return -1;
+		}
+	}
+	errno = old_errno;
+
+	if FUNCTION_SANDBOX_SAFE_OPEN_INT_AT(dirfd, STRING_NAME, pathname, flags) {
+		check_dlsym(WRAPPER_TRUE_NAME, WRAPPER_SYMNAME,
+			    WRAPPER_SYMVER);
+		if (flags & O_CREAT)
+			result = WRAPPER_TRUE_NAME(dirfd, pathname, flags, mode);
+		else
+			result = WRAPPER_TRUE_NAME(dirfd, pathname, flags);
+	}
+
+	return result;
+}