1 files changed, 63 insertions, 0 deletions
diff --git a/include/linux/ucopysize.h b/include/linux/ucopysize.h
new file mode 100644
index 000000000000..41c2d9720466
--- /dev/null
+++ b/include/linux/ucopysize.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Perform sanity checking for object sizes for uaccess.h and uio.h. */
+#ifndef __LINUX_UCOPYSIZE_H__
+#define __LINUX_UCOPYSIZE_H__
+
+#include <linux/bug.h>
+
+#ifdef CONFIG_HARDENED_USERCOPY
+#include <linux/jump_label.h>
+extern void __check_object_size(const void *ptr, unsigned long n,
+					bool to_user);
+
+DECLARE_STATIC_KEY_MAYBE(CONFIG_HARDENED_USERCOPY_DEFAULT_ON,
+			   validate_usercopy_range);
+
+static __always_inline void check_object_size(const void *ptr, unsigned long n,
+					      bool to_user)
+{
+	if (!__builtin_constant_p(n) &&
+	    static_branch_maybe(CONFIG_HARDENED_USERCOPY_DEFAULT_ON,
+				&validate_usercopy_range)) {
+		__check_object_size(ptr, n, to_user);
+	}
+}
+#else
+static inline void check_object_size(const void *ptr, unsigned long n,
+				     bool to_user)
+{ }
+#endif /* CONFIG_HARDENED_USERCOPY */
+
+extern void __compiletime_error("copy source size is too small")
+__bad_copy_from(void);
+extern void __compiletime_error("copy destination size is too small")
+__bad_copy_to(void);
+
+void __copy_overflow(int size, unsigned long count);
+
+static inline void copy_overflow(int size, unsigned long count)
+{
+	if (IS_ENABLED(CONFIG_BUG))
+		__copy_overflow(size, count);
+}
+
+static __always_inline __must_check bool
+check_copy_size(const void *addr, size_t bytes, bool is_source)
+{
+	int sz = __builtin_object_size(addr, 0);
+	if (unlikely(sz >= 0 && sz < bytes)) {
+		if (!__builtin_constant_p(bytes))
+			copy_overflow(sz, bytes);
+		else if (is_source)
+			__bad_copy_from();
+		else
+			__bad_copy_to();
+		return false;
+	}
+	if (WARN_ON_ONCE(bytes > INT_MAX))
+		return false;
+	check_object_size(addr, bytes, is_source);
+	return true;
+}
+
+#endif /* __LINUX_UCOPYSIZE_H__ */