1 files changed, 65 insertions, 0 deletions
diff --git a/libsandbox/pre_check_mkdirat.c b/libsandbox/pre_check_mkdirat.c
new file mode 100644
index 0000000..49c382a
--- /dev/null
+++ b/libsandbox/pre_check_mkdirat.c
@@ -0,0 +1,65 @@
+/*
+ * mkdir*() pre-check.
+ *
+ * Copyright 1999-2012 Gentoo Foundation
+ * Licensed under the GPL-2
+ */
+
+#include "headers.h"
+#include "sbutil.h"
+#include "libsandbox.h"
+#include "wrappers.h"
+
+bool sb_mkdirat_pre_check(const char *func, const char *pathname, int dirfd)
+{
+	char canonic[SB_PATH_MAX];
+
+	save_errno();
+
+	/* Check incoming args against common *at issues */
+	char dirfd_path[SB_PATH_MAX];
+	if (!sb_common_at_pre_check(func, &pathname, dirfd, dirfd_path, sizeof(dirfd_path)))
+		return false;
+
+	/* Then break down any relative/symlink paths */
+	if (-1 == canonicalize(pathname, canonic))
+		/* see comments in check_syscall() */
+		if (ENAMETOOLONG != errno) {
+			sb_debug_dyn("EARLY FAIL: %s(%s) @ canonicalize: %s\n",
+				func, pathname, strerror(errno));
+			return false;
+		}
+
+	/* XXX: Hack to prevent errors if the directory exist, and are
+	 * not writable - we rather return EEXIST than fail.  This can
+	 * occur if doing something like `mkdir -p /`.  We certainly do
+	 * not want to pass this attempt up to the higher levels as those
+	 * will trigger a sandbox violation.
+	 */
+	struct stat64 st;
+	if (0 == lstat64(pathname, &st)) {
+		int new_errno;
+		sb_debug_dyn("EARLY FAIL: %s(%s[%s]) @ lstat: %s\n",
+			func, pathname, canonic, strerror(errno));
+
+		new_errno = EEXIST;
+
+		/* Hmm, is this a broken symlink we're trying to extend ? */
+		if (S_ISLNK(st.st_mode) && stat64(pathname, &st) != 0) {
+			/* XXX: This awful hack should probably be turned into a
+			 * common func that does a better job.  For now, we have
+			 * enough crap to catch gnulib tests #297026.
+			 */
+			char *parent = strrchr(pathname, '/');
+			if (parent && (strcmp(parent, "/.") == 0 || strcmp(parent, "/..") == 0))
+				new_errno = ENOENT;
+		}
+
+		errno = new_errno;
+		return false;
+	}
+
+	restore_errno();
+
+	return true;
+}