ucopysize.h

 1/* SPDX-License-Identifier: GPL-2.0 */
 2/* Perform sanity checking for object sizes for uaccess.h and uio.h. */
 3#ifndef __LINUX_UCOPYSIZE_H__
 4#define __LINUX_UCOPYSIZE_H__
 5
 6#include <linux/bug.h>
 7
 8#ifdef CONFIG_HARDENED_USERCOPY
 9#include <linux/jump_label.h>
10extern void __check_object_size(const void *ptr, unsigned long n,
11					bool to_user);
12
13DECLARE_STATIC_KEY_MAYBE(CONFIG_HARDENED_USERCOPY_DEFAULT_ON,
14			   validate_usercopy_range);
15
16static __always_inline void check_object_size(const void *ptr, unsigned long n,
17					      bool to_user)
18{
19	if (!__builtin_constant_p(n) &&
20	    static_branch_maybe(CONFIG_HARDENED_USERCOPY_DEFAULT_ON,
21				&validate_usercopy_range)) {
22		__check_object_size(ptr, n, to_user);
23	}
24}
25#else
26static inline void check_object_size(const void *ptr, unsigned long n,
27				     bool to_user)
28{ }
29#endif /* CONFIG_HARDENED_USERCOPY */
30
31extern void __compiletime_error("copy source size is too small")
32__bad_copy_from(void);
33extern void __compiletime_error("copy destination size is too small")
34__bad_copy_to(void);
35
36void __copy_overflow(int size, unsigned long count);
37
38static inline void copy_overflow(int size, unsigned long count)
39{
40	if (IS_ENABLED(CONFIG_BUG))
41		__copy_overflow(size, count);
42}
43
44static __always_inline __must_check bool
45check_copy_size(const void *addr, size_t bytes, bool is_source)
46{
47	int sz = __builtin_object_size(addr, 0);
48	if (unlikely(sz >= 0 && sz < bytes)) {
49		if (!__builtin_constant_p(bytes))
50			copy_overflow(sz, bytes);
51		else if (is_source)
52			__bad_copy_from();
53		else
54			__bad_copy_to();
55		return false;
56	}
57	if (WARN_ON_ONCE(bytes > INT_MAX))
58		return false;
59	check_object_size(addr, bytes, is_source);
60	return true;
61}
62
63#endif /* __LINUX_UCOPYSIZE_H__ */