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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Access kernel or user memory without faulting.
4 */
5#include <linux/export.h>
6#include <linux/mm.h>
7#include <linux/uaccess.h>
8
9bool __weak copy_from_kernel_nofault_allowed(const void *unsafe_src,
10 size_t size)
11{
12 return true;
13}
14
15#define copy_from_kernel_nofault_loop(dst, src, len, type, err_label) \
16 while (len >= sizeof(type)) { \
17 __get_kernel_nofault(dst, src, type, err_label); \
18 dst += sizeof(type); \
19 src += sizeof(type); \
20 len -= sizeof(type); \
21 }
22
23long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
24{
25 unsigned long align = 0;
26
27 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
28 align = (unsigned long)dst | (unsigned long)src;
29
30 if (!copy_from_kernel_nofault_allowed(src, size))
31 return -ERANGE;
32
33 pagefault_disable();
34 if (!(align & 7))
35 copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
36 if (!(align & 3))
37 copy_from_kernel_nofault_loop(dst, src, size, u32, Efault);
38 if (!(align & 1))
39 copy_from_kernel_nofault_loop(dst, src, size, u16, Efault);
40 copy_from_kernel_nofault_loop(dst, src, size, u8, Efault);
41 pagefault_enable();
42 return 0;
43Efault:
44 pagefault_enable();
45 return -EFAULT;
46}
47EXPORT_SYMBOL_GPL(copy_from_kernel_nofault);
48
49#define copy_to_kernel_nofault_loop(dst, src, len, type, err_label) \
50 while (len >= sizeof(type)) { \
51 __put_kernel_nofault(dst, src, type, err_label); \
52 dst += sizeof(type); \
53 src += sizeof(type); \
54 len -= sizeof(type); \
55 }
56
57long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
58{
59 unsigned long align = 0;
60
61 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
62 align = (unsigned long)dst | (unsigned long)src;
63
64 pagefault_disable();
65 if (!(align & 7))
66 copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);
67 if (!(align & 3))
68 copy_to_kernel_nofault_loop(dst, src, size, u32, Efault);
69 if (!(align & 1))
70 copy_to_kernel_nofault_loop(dst, src, size, u16, Efault);
71 copy_to_kernel_nofault_loop(dst, src, size, u8, Efault);
72 pagefault_enable();
73 return 0;
74Efault:
75 pagefault_enable();
76 return -EFAULT;
77}
78
79long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
80{
81 const void *src = unsafe_addr;
82
83 if (unlikely(count <= 0))
84 return 0;
85 if (!copy_from_kernel_nofault_allowed(unsafe_addr, count))
86 return -ERANGE;
87
88 pagefault_disable();
89 do {
90 __get_kernel_nofault(dst, src, u8, Efault);
91 dst++;
92 src++;
93 } while (dst[-1] && src - unsafe_addr < count);
94 pagefault_enable();
95
96 dst[-1] = '\0';
97 return src - unsafe_addr;
98Efault:
99 pagefault_enable();
100 dst[0] = '\0';
101 return -EFAULT;
102}
103
104/**
105 * copy_from_user_nofault(): safely attempt to read from a user-space location
106 * @dst: pointer to the buffer that shall take the data
107 * @src: address to read from. This must be a user address.
108 * @size: size of the data chunk
109 *
110 * Safely read from user address @src to the buffer at @dst. If a kernel fault
111 * happens, handle that and return -EFAULT.
112 */
113long copy_from_user_nofault(void *dst, const void __user *src, size_t size)
114{
115 long ret = -EFAULT;
116 if (access_ok(src, size)) {
117 pagefault_disable();
118 ret = __copy_from_user_inatomic(dst, src, size);
119 pagefault_enable();
120 }
121
122 if (ret)
123 return -EFAULT;
124 return 0;
125}
126EXPORT_SYMBOL_GPL(copy_from_user_nofault);
127
128/**
129 * copy_to_user_nofault(): safely attempt to write to a user-space location
130 * @dst: address to write to
131 * @src: pointer to the data that shall be written
132 * @size: size of the data chunk
133 *
134 * Safely write to address @dst from the buffer at @src. If a kernel fault
135 * happens, handle that and return -EFAULT.
136 */
137long copy_to_user_nofault(void __user *dst, const void *src, size_t size)
138{
139 long ret = -EFAULT;
140
141 if (access_ok(dst, size)) {
142 pagefault_disable();
143 ret = __copy_to_user_inatomic(dst, src, size);
144 pagefault_enable();
145 }
146
147 if (ret)
148 return -EFAULT;
149 return 0;
150}
151EXPORT_SYMBOL_GPL(copy_to_user_nofault);
152
153/**
154 * strncpy_from_user_nofault: - Copy a NUL terminated string from unsafe user
155 * address.
156 * @dst: Destination address, in kernel space. This buffer must be at
157 * least @count bytes long.
158 * @unsafe_addr: Unsafe user address.
159 * @count: Maximum number of bytes to copy, including the trailing NUL.
160 *
161 * Copies a NUL-terminated string from unsafe user address to kernel buffer.
162 *
163 * On success, returns the length of the string INCLUDING the trailing NUL.
164 *
165 * If access fails, returns -EFAULT (some data may have been copied
166 * and the trailing NUL added).
167 *
168 * If @count is smaller than the length of the string, copies @count-1 bytes,
169 * sets the last byte of @dst buffer to NUL and returns @count.
170 */
171long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
172 long count)
173{
174 long ret;
175
176 if (unlikely(count <= 0))
177 return 0;
178
179 pagefault_disable();
180 ret = strncpy_from_user(dst, unsafe_addr, count);
181 pagefault_enable();
182
183 if (ret >= count) {
184 ret = count;
185 dst[ret - 1] = '\0';
186 } else if (ret > 0) {
187 ret++;
188 }
189
190 return ret;
191}
192
193/**
194 * strnlen_user_nofault: - Get the size of a user string INCLUDING final NUL.
195 * @unsafe_addr: The string to measure.
196 * @count: Maximum count (including NUL)
197 *
198 * Get the size of a NUL-terminated string in user space without pagefault.
199 *
200 * Returns the size of the string INCLUDING the terminating NUL.
201 *
202 * If the string is too long, returns a number larger than @count. User
203 * has to check the return value against "> count".
204 * On exception (or invalid count), returns 0.
205 *
206 * Unlike strnlen_user, this can be used from IRQ handler etc. because
207 * it disables pagefaults.
208 */
209long strnlen_user_nofault(const void __user *unsafe_addr, long count)
210{
211 int ret;
212
213 pagefault_disable();
214 ret = strnlen_user(unsafe_addr, count);
215 pagefault_enable();
216
217 return ret;
218}
219
220void __copy_overflow(int size, unsigned long count)
221{
222 WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
223}
224EXPORT_SYMBOL(__copy_overflow);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Access kernel or user memory without faulting.
4 */
5#include <linux/export.h>
6#include <linux/mm.h>
7#include <linux/uaccess.h>
8#include <asm/tlb.h>
9
10bool __weak copy_from_kernel_nofault_allowed(const void *unsafe_src,
11 size_t size)
12{
13 return true;
14}
15
16#define copy_from_kernel_nofault_loop(dst, src, len, type, err_label) \
17 while (len >= sizeof(type)) { \
18 __get_kernel_nofault(dst, src, type, err_label); \
19 dst += sizeof(type); \
20 src += sizeof(type); \
21 len -= sizeof(type); \
22 }
23
24long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
25{
26 unsigned long align = 0;
27
28 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
29 align = (unsigned long)dst | (unsigned long)src;
30
31 if (!copy_from_kernel_nofault_allowed(src, size))
32 return -ERANGE;
33
34 pagefault_disable();
35 if (!(align & 7))
36 copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
37 if (!(align & 3))
38 copy_from_kernel_nofault_loop(dst, src, size, u32, Efault);
39 if (!(align & 1))
40 copy_from_kernel_nofault_loop(dst, src, size, u16, Efault);
41 copy_from_kernel_nofault_loop(dst, src, size, u8, Efault);
42 pagefault_enable();
43 return 0;
44Efault:
45 pagefault_enable();
46 return -EFAULT;
47}
48EXPORT_SYMBOL_GPL(copy_from_kernel_nofault);
49
50#define copy_to_kernel_nofault_loop(dst, src, len, type, err_label) \
51 while (len >= sizeof(type)) { \
52 __put_kernel_nofault(dst, src, type, err_label); \
53 dst += sizeof(type); \
54 src += sizeof(type); \
55 len -= sizeof(type); \
56 }
57
58long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
59{
60 unsigned long align = 0;
61
62 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
63 align = (unsigned long)dst | (unsigned long)src;
64
65 pagefault_disable();
66 if (!(align & 7))
67 copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);
68 if (!(align & 3))
69 copy_to_kernel_nofault_loop(dst, src, size, u32, Efault);
70 if (!(align & 1))
71 copy_to_kernel_nofault_loop(dst, src, size, u16, Efault);
72 copy_to_kernel_nofault_loop(dst, src, size, u8, Efault);
73 pagefault_enable();
74 return 0;
75Efault:
76 pagefault_enable();
77 return -EFAULT;
78}
79
80long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
81{
82 const void *src = unsafe_addr;
83
84 if (unlikely(count <= 0))
85 return 0;
86 if (!copy_from_kernel_nofault_allowed(unsafe_addr, count))
87 return -ERANGE;
88
89 pagefault_disable();
90 do {
91 __get_kernel_nofault(dst, src, u8, Efault);
92 dst++;
93 src++;
94 } while (dst[-1] && src - unsafe_addr < count);
95 pagefault_enable();
96
97 dst[-1] = '\0';
98 return src - unsafe_addr;
99Efault:
100 pagefault_enable();
101 dst[0] = '\0';
102 return -EFAULT;
103}
104
105/**
106 * copy_from_user_nofault(): safely attempt to read from a user-space location
107 * @dst: pointer to the buffer that shall take the data
108 * @src: address to read from. This must be a user address.
109 * @size: size of the data chunk
110 *
111 * Safely read from user address @src to the buffer at @dst. If a kernel fault
112 * happens, handle that and return -EFAULT.
113 */
114long copy_from_user_nofault(void *dst, const void __user *src, size_t size)
115{
116 long ret = -EFAULT;
117
118 if (!__access_ok(src, size))
119 return ret;
120
121 if (!nmi_uaccess_okay())
122 return ret;
123
124 pagefault_disable();
125 ret = __copy_from_user_inatomic(dst, src, size);
126 pagefault_enable();
127
128 if (ret)
129 return -EFAULT;
130 return 0;
131}
132EXPORT_SYMBOL_GPL(copy_from_user_nofault);
133
134/**
135 * copy_to_user_nofault(): safely attempt to write to a user-space location
136 * @dst: address to write to
137 * @src: pointer to the data that shall be written
138 * @size: size of the data chunk
139 *
140 * Safely write to address @dst from the buffer at @src. If a kernel fault
141 * happens, handle that and return -EFAULT.
142 */
143long copy_to_user_nofault(void __user *dst, const void *src, size_t size)
144{
145 long ret = -EFAULT;
146
147 if (access_ok(dst, size)) {
148 pagefault_disable();
149 ret = __copy_to_user_inatomic(dst, src, size);
150 pagefault_enable();
151 }
152
153 if (ret)
154 return -EFAULT;
155 return 0;
156}
157EXPORT_SYMBOL_GPL(copy_to_user_nofault);
158
159/**
160 * strncpy_from_user_nofault: - Copy a NUL terminated string from unsafe user
161 * address.
162 * @dst: Destination address, in kernel space. This buffer must be at
163 * least @count bytes long.
164 * @unsafe_addr: Unsafe user address.
165 * @count: Maximum number of bytes to copy, including the trailing NUL.
166 *
167 * Copies a NUL-terminated string from unsafe user address to kernel buffer.
168 *
169 * On success, returns the length of the string INCLUDING the trailing NUL.
170 *
171 * If access fails, returns -EFAULT (some data may have been copied
172 * and the trailing NUL added).
173 *
174 * If @count is smaller than the length of the string, copies @count-1 bytes,
175 * sets the last byte of @dst buffer to NUL and returns @count.
176 */
177long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
178 long count)
179{
180 long ret;
181
182 if (unlikely(count <= 0))
183 return 0;
184
185 pagefault_disable();
186 ret = strncpy_from_user(dst, unsafe_addr, count);
187 pagefault_enable();
188
189 if (ret >= count) {
190 ret = count;
191 dst[ret - 1] = '\0';
192 } else if (ret > 0) {
193 ret++;
194 }
195
196 return ret;
197}
198
199/**
200 * strnlen_user_nofault: - Get the size of a user string INCLUDING final NUL.
201 * @unsafe_addr: The string to measure.
202 * @count: Maximum count (including NUL)
203 *
204 * Get the size of a NUL-terminated string in user space without pagefault.
205 *
206 * Returns the size of the string INCLUDING the terminating NUL.
207 *
208 * If the string is too long, returns a number larger than @count. User
209 * has to check the return value against "> count".
210 * On exception (or invalid count), returns 0.
211 *
212 * Unlike strnlen_user, this can be used from IRQ handler etc. because
213 * it disables pagefaults.
214 */
215long strnlen_user_nofault(const void __user *unsafe_addr, long count)
216{
217 int ret;
218
219 pagefault_disable();
220 ret = strnlen_user(unsafe_addr, count);
221 pagefault_enable();
222
223 return ret;
224}
225
226void __copy_overflow(int size, unsigned long count)
227{
228 WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
229}
230EXPORT_SYMBOL(__copy_overflow);