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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(size: sz, count: 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(ptr: addr, n: bytes, to_user: is_source);
60 return true;
61}
62
63#endif /* __LINUX_UCOPYSIZE_H__ */
64

source code of linux/include/linux/ucopysize.h