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
14 typedef struct {
15 union {
16 void *kernel;
17 void __user *user;
18 };
19 bool is_kernel : 1;
20 } sockptr_t;
21
sockptr_is_kernel(sockptr_t sockptr)22 static inline bool sockptr_is_kernel(sockptr_t sockptr)
23 {
24 return sockptr.is_kernel;
25 }
26
KERNEL_SOCKPTR(void * p)27 static inline sockptr_t KERNEL_SOCKPTR(void *p)
28 {
29 return (sockptr_t) { .kernel = p, .is_kernel = true };
30 }
31
USER_SOCKPTR(void __user * p)32 static inline sockptr_t USER_SOCKPTR(void __user *p)
33 {
34 return (sockptr_t) { .user = p };
35 }
36
sockptr_is_null(sockptr_t sockptr)37 static 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
copy_from_sockptr_offset(void * dst,sockptr_t src,size_t offset,size_t size)44 static 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
53 /* Deprecated.
54 * This is unsafe, unless caller checked user provided optlen.
55 * Prefer copy_safe_from_sockptr() instead.
56 */
copy_from_sockptr(void * dst,sockptr_t src,size_t size)57 static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size)
58 {
59 return copy_from_sockptr_offset(dst, src, 0, size);
60 }
61
62 /**
63 * copy_safe_from_sockptr: copy a struct from sockptr
64 * @dst: Destination address, in kernel space. This buffer must be @ksize
65 * bytes long.
66 * @ksize: Size of @dst struct.
67 * @optval: Source address. (in user or kernel space)
68 * @optlen: Size of @optval data.
69 *
70 * Returns:
71 * * -EINVAL: @optlen < @ksize
72 * * -EFAULT: access to userspace failed.
73 * * 0 : @ksize bytes were copied
74 */
copy_safe_from_sockptr(void * dst,size_t ksize,sockptr_t optval,unsigned int optlen)75 static inline int copy_safe_from_sockptr(void *dst, size_t ksize,
76 sockptr_t optval, unsigned int optlen)
77 {
78 if (optlen < ksize)
79 return -EINVAL;
80 if (copy_from_sockptr(dst, optval, ksize))
81 return -EFAULT;
82 return 0;
83 }
84
copy_struct_from_sockptr(void * dst,size_t ksize,sockptr_t src,size_t usize)85 static inline int copy_struct_from_sockptr(void *dst, size_t ksize,
86 sockptr_t src, size_t usize)
87 {
88 size_t size = min(ksize, usize);
89 size_t rest = max(ksize, usize) - size;
90
91 if (!sockptr_is_kernel(src))
92 return copy_struct_from_user(dst, ksize, src.user, size);
93
94 if (usize < ksize) {
95 memset(dst + size, 0, rest);
96 } else if (usize > ksize) {
97 char *p = src.kernel;
98
99 while (rest--) {
100 if (*p++)
101 return -E2BIG;
102 }
103 }
104 memcpy(dst, src.kernel, size);
105 return 0;
106 }
107
copy_to_sockptr_offset(sockptr_t dst,size_t offset,const void * src,size_t size)108 static inline int copy_to_sockptr_offset(sockptr_t dst, size_t offset,
109 const void *src, size_t size)
110 {
111 if (!sockptr_is_kernel(dst))
112 return copy_to_user(dst.user + offset, src, size);
113 memcpy(dst.kernel + offset, src, size);
114 return 0;
115 }
116
copy_to_sockptr(sockptr_t dst,const void * src,size_t size)117 static inline int copy_to_sockptr(sockptr_t dst, const void *src, size_t size)
118 {
119 return copy_to_sockptr_offset(dst, 0, src, size);
120 }
121
memdup_sockptr_noprof(sockptr_t src,size_t len)122 static inline void *memdup_sockptr_noprof(sockptr_t src, size_t len)
123 {
124 void *p = kmalloc_track_caller_noprof(len, GFP_USER | __GFP_NOWARN);
125
126 if (!p)
127 return ERR_PTR(-ENOMEM);
128 if (copy_from_sockptr(p, src, len)) {
129 kfree(p);
130 return ERR_PTR(-EFAULT);
131 }
132 return p;
133 }
134 #define memdup_sockptr(...) alloc_hooks(memdup_sockptr_noprof(__VA_ARGS__))
135
memdup_sockptr_nul_noprof(sockptr_t src,size_t len)136 static inline void *memdup_sockptr_nul_noprof(sockptr_t src, size_t len)
137 {
138 char *p = kmalloc_track_caller_noprof(len + 1, GFP_KERNEL);
139
140 if (!p)
141 return ERR_PTR(-ENOMEM);
142 if (copy_from_sockptr(p, src, len)) {
143 kfree(p);
144 return ERR_PTR(-EFAULT);
145 }
146 p[len] = '\0';
147 return p;
148 }
149 #define memdup_sockptr_nul(...) alloc_hooks(memdup_sockptr_nul_noprof(__VA_ARGS__))
150
strncpy_from_sockptr(char * dst,sockptr_t src,size_t count)151 static inline long strncpy_from_sockptr(char *dst, sockptr_t src, size_t count)
152 {
153 if (sockptr_is_kernel(src)) {
154 size_t len = min(strnlen(src.kernel, count - 1) + 1, count);
155
156 memcpy(dst, src.kernel, len);
157 return len;
158 }
159 return strncpy_from_user(dst, src.user, count);
160 }
161
check_zeroed_sockptr(sockptr_t src,size_t offset,size_t size)162 static inline int check_zeroed_sockptr(sockptr_t src, size_t offset,
163 size_t size)
164 {
165 if (!sockptr_is_kernel(src))
166 return check_zeroed_user(src.user + offset, size);
167 return memchr_inv(src.kernel + offset, 0, size) == NULL;
168 }
169
170 #endif /* _LINUX_SOCKPTR_H */
171