Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (c) 2020 Christoph Hellwig.
4 *
5 * Support for "universal" pointers that can point to either kernel or userspace
6 * memory.
7 */
8#ifndef _LINUX_SOCKPTR_H
9#define _LINUX_SOCKPTR_H
10
11#include <linux/slab.h>
12#include <linux/uaccess.h>
13
14typedef struct {
15 union {
16 void *kernel;
17 void __user *user;
18 };
19 bool is_kernel : 1;
20} sockptr_t;
21
22static inline bool sockptr_is_kernel(sockptr_t sockptr)
23{
24 return sockptr.is_kernel;
25}
26
27static inline sockptr_t KERNEL_SOCKPTR(void *p)
28{
29 return (sockptr_t) { .kernel = p, .is_kernel = true };
30}
31
32static inline sockptr_t USER_SOCKPTR(void __user *p)
33{
34 return (sockptr_t) { .user = p };
35}
36
37static inline bool sockptr_is_null(sockptr_t sockptr)
38{
39 if (sockptr_is_kernel(sockptr))
40 return !sockptr.kernel;
41 return !sockptr.user;
42}
43
44static inline int copy_from_sockptr_offset(void *dst, sockptr_t src,
45 size_t offset, size_t size)
46{
47 if (!sockptr_is_kernel(src))
48 return copy_from_user(dst, src.user + offset, size);
49 memcpy(dst, src.kernel + offset, size);
50 return 0;
51}
52
53static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size)
54{
55 return copy_from_sockptr_offset(dst, src, 0, size);
56}
57
58static inline int copy_struct_from_sockptr(void *dst, size_t ksize,
59 sockptr_t src, size_t usize)
60{
61 size_t size = min(ksize, usize);
62 size_t rest = max(ksize, usize) - size;
63
64 if (!sockptr_is_kernel(src))
65 return copy_struct_from_user(dst, ksize, src.user, size);
66
67 if (usize < ksize) {
68 memset(dst + size, 0, rest);
69 } else if (usize > ksize) {
70 char *p = src.kernel;
71
72 while (rest--) {
73 if (*p++)
74 return -E2BIG;
75 }
76 }
77 memcpy(dst, src.kernel, size);
78 return 0;
79}
80
81static inline int copy_to_sockptr_offset(sockptr_t dst, size_t offset,
82 const void *src, size_t size)
83{
84 if (!sockptr_is_kernel(dst))
85 return copy_to_user(dst.user + offset, src, size);
86 memcpy(dst.kernel + offset, src, size);
87 return 0;
88}
89
90static inline int copy_to_sockptr(sockptr_t dst, const void *src, size_t size)
91{
92 return copy_to_sockptr_offset(dst, 0, src, size);
93}
94
95static inline void *memdup_sockptr(sockptr_t src, size_t len)
96{
97 void *p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);
98
99 if (!p)
100 return ERR_PTR(-ENOMEM);
101 if (copy_from_sockptr(p, src, len)) {
102 kfree(p);
103 return ERR_PTR(-EFAULT);
104 }
105 return p;
106}
107
108static inline void *memdup_sockptr_nul(sockptr_t src, size_t len)
109{
110 char *p = kmalloc_track_caller(len + 1, GFP_KERNEL);
111
112 if (!p)
113 return ERR_PTR(-ENOMEM);
114 if (copy_from_sockptr(p, src, len)) {
115 kfree(p);
116 return ERR_PTR(-EFAULT);
117 }
118 p[len] = '\0';
119 return p;
120}
121
122static inline long strncpy_from_sockptr(char *dst, sockptr_t src, size_t count)
123{
124 if (sockptr_is_kernel(src)) {
125 size_t len = min(strnlen(src.kernel, count - 1) + 1, count);
126
127 memcpy(dst, src.kernel, len);
128 return len;
129 }
130 return strncpy_from_user(dst, src.user, count);
131}
132
133static inline int check_zeroed_sockptr(sockptr_t src, size_t offset,
134 size_t size)
135{
136 if (!sockptr_is_kernel(src))
137 return check_zeroed_user(src.user + offset, size);
138 return memchr_inv(src.kernel + offset, 0, size) == NULL;
139}
140
141#endif /* _LINUX_SOCKPTR_H */