aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm64/include/asm/uaccess.h
blob: bf8435deb8a1f135a4fca0550bd13535a5c049e3 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
/*
 * Based on arch/arm/include/asm/uaccess.h
 *
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef __ASM_UACCESS_H
#define __ASM_UACCESS_H

#include <asm/alternative.h>
#include <asm/kernel-pgtable.h>
#include <asm/sysreg.h>

/*
 * User space memory access functions
 */
#include <linux/bitops.h>
#include <linux/kasan-checks.h>
#include <linux/string.h>

#include <asm/cpufeature.h>
#include <asm/ptrace.h>
#include <asm/memory.h>
#include <asm/compiler.h>
#include <asm/extable.h>

#define KERNEL_DS	(-1UL)
#define get_ds()	(KERNEL_DS)

#define USER_DS		TASK_SIZE_64
#define get_fs()	(current_thread_info()->addr_limit)

static inline void set_fs(mm_segment_t fs)
{
	current_thread_info()->addr_limit = fs;

	/*
	 * Enable/disable UAO so that copy_to_user() etc can access
	 * kernel memory with the unprivileged instructions.
	 */
	if (IS_ENABLED(CONFIG_ARM64_UAO) && fs == KERNEL_DS)
		asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO));
	else
		asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO,
				CONFIG_ARM64_UAO));
}

#define segment_eq(a, b)	((a) == (b))

/*
 * Test whether a block of memory is a valid user space address.
 * Returns 1 if the range is valid, 0 otherwise.
 *
 * This is equivalent to the following test:
 * (u65)addr + (u65)size <= current->addr_limit
 *
 * This needs 65-bit arithmetic.
 */
#define __range_ok(addr, size)						\
({									\
	unsigned long __addr = (unsigned long)(addr);			\
	unsigned long flag, roksum;					\
	__chk_user_ptr(addr);						\
	asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls"		\
		: "=&r" (flag), "=&r" (roksum)				\
		: "1" (__addr), "Ir" (size),				\
		  "r" (current_thread_info()->addr_limit)		\
		: "cc");						\
	flag;								\
})

/*
 * When dealing with data aborts, watchpoints, or instruction traps we may end
 * up with a tagged userland pointer. Clear the tag to get a sane pointer to
 * pass on to access_ok(), for instance.
 */
#define untagged_addr(addr)		sign_extend64(addr, 55)

#define access_ok(type, addr, size)	__range_ok(addr, size)
#define user_addr_max			get_fs

#define _ASM_EXTABLE(from, to)						\
	"	.pushsection	__ex_table, \"a\"\n"			\
	"	.align		3\n"					\
	"	.long		(" #from " - .), (" #to " - .)\n"	\
	"	.popsection\n"

/*
 * User access enabling/disabling.
 */
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
static inline void __uaccess_ttbr0_disable(void)
{
	unsigned long ttbr;

	/* reserved_ttbr0 placed at the end of swapper_pg_dir */
	ttbr = read_sysreg(ttbr1_el1) + SWAPPER_DIR_SIZE;
	write_sysreg(ttbr, ttbr0_el1);
	isb();
}

static inline void __uaccess_ttbr0_enable(void)
{
	unsigned long flags;

	/*
	 * Disable interrupts to avoid preemption between reading the 'ttbr0'
	 * variable and the MSR. A context switch could trigger an ASID
	 * roll-over and an update of 'ttbr0'.
	 */
	local_irq_save(flags);
	write_sysreg(current_thread_info()->ttbr0, ttbr0_el1);
	isb();
	local_irq_restore(flags);
}

static inline bool uaccess_ttbr0_disable(void)
{
	if (!system_uses_ttbr0_pan())
		return false;
	__uaccess_ttbr0_disable();
	return true;
}

static inline bool uaccess_ttbr0_enable(void)
{
	if (!system_uses_ttbr0_pan())
		return false;
	__uaccess_ttbr0_enable();
	return true;
}
#else
static inline bool uaccess_ttbr0_disable(void)
{
	return false;
}

static inline bool uaccess_ttbr0_enable(void)
{
	return false;
}
#endif

#define __uaccess_disable(alt)						\
do {									\
	if (!uaccess_ttbr0_disable())					\
		asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), alt,		\
				CONFIG_ARM64_PAN));			\
} while (0)

#define __uaccess_enable(alt)						\
do {									\
	if (!uaccess_ttbr0_enable())					\
		asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), alt,		\
				CONFIG_ARM64_PAN));			\
} while (0)

static inline void uaccess_disable(void)
{
	__uaccess_disable(ARM64_HAS_PAN);
}

static inline void uaccess_enable(void)
{
	__uaccess_enable(ARM64_HAS_PAN);
}

/*
 * These functions are no-ops when UAO is present.
 */
static inline void uaccess_disable_not_uao(void)
{
	__uaccess_disable(ARM64_ALT_PAN_NOT_UAO);
}

static inline void uaccess_enable_not_uao(void)
{
	__uaccess_enable(ARM64_ALT_PAN_NOT_UAO);
}

/*
 * The "__xxx" versions of the user access functions do not verify the address
 * space - it must have been done previously with a separate "access_ok()"
 * call.
 *
 * The "__xxx_error" versions set the third argument to -EFAULT if an error
 * occurs, and leave it unchanged on success.
 */
#define __get_user_asm(instr, alt_instr, reg, x, addr, err, feature)	\
	asm volatile(							\
	"1:"ALTERNATIVE(instr "     " reg "1, [%2]\n",			\
			alt_instr " " reg "1, [%2]\n", feature)		\
	"2:\n"								\
	"	.section .fixup, \"ax\"\n"				\
	"	.align	2\n"						\
	"3:	mov	%w0, %3\n"					\
	"	mov	%1, #0\n"					\
	"	b	2b\n"						\
	"	.previous\n"						\
	_ASM_EXTABLE(1b, 3b)						\
	: "+r" (err), "=&r" (x)						\
	: "r" (addr), "i" (-EFAULT))

#define __get_user_err(x, ptr, err)					\
do {									\
	unsigned long __gu_val;						\
	__chk_user_ptr(ptr);						\
	uaccess_enable_not_uao();					\
	switch (sizeof(*(ptr))) {					\
	case 1:								\
		__get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr),  \
			       (err), ARM64_HAS_UAO);			\
		break;							\
	case 2:								\
		__get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr),  \
			       (err), ARM64_HAS_UAO);			\
		break;							\
	case 4:								\
		__get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr),	\
			       (err), ARM64_HAS_UAO);			\
		break;							\
	case 8:								\
		__get_user_asm("ldr", "ldtr", "%x",  __gu_val, (ptr),	\
			       (err), ARM64_HAS_UAO);			\
		break;							\
	default:							\
		BUILD_BUG();						\
	}								\
	uaccess_disable_not_uao();					\
	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
} while (0)

#define __get_user(x, ptr)						\
({									\
	int __gu_err = 0;						\
	__get_user_err((x), (ptr), __gu_err);				\
	__gu_err;							\
})

#define __get_user_error(x, ptr, err)					\
({									\
	__get_user_err((x), (ptr), (err));				\
	(void)0;							\
})

#define get_user(x, ptr)						\
({									\
	__typeof__(*(ptr)) __user *__p = (ptr);				\
	might_fault();							\
	access_ok(VERIFY_READ, __p, sizeof(*__p)) ?			\
		__get_user((x), __p) :					\
		((x) = 0, -EFAULT);					\
})

#define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature)	\
	asm volatile(							\
	"1:"ALTERNATIVE(instr "     " reg "1, [%2]\n",			\
			alt_instr " " reg "1, [%2]\n", feature)		\
	"2:\n"								\
	"	.section .fixup,\"ax\"\n"				\
	"	.align	2\n"						\
	"3:	mov	%w0, %3\n"					\
	"	b	2b\n"						\
	"	.previous\n"						\
	_ASM_EXTABLE(1b, 3b)						\
	: "+r" (err)							\
	: "r" (x), "r" (addr), "i" (-EFAULT))

#define __put_user_err(x, ptr, err)					\
do {									\
	__typeof__(*(ptr)) __pu_val = (x);				\
	__chk_user_ptr(ptr);						\
	uaccess_enable_not_uao();					\
	switch (sizeof(*(ptr))) {					\
	case 1:								\
		__put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr),	\
			       (err), ARM64_HAS_UAO);			\
		break;							\
	case 2:								\
		__put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr),	\
			       (err), ARM64_HAS_UAO);			\
		break;							\
	case 4:								\
		__put_user_asm("str", "sttr", "%w", __pu_val, (ptr),	\
			       (err), ARM64_HAS_UAO);			\
		break;							\
	case 8:								\
		__put_user_asm("str", "sttr", "%x", __pu_val, (ptr),	\
			       (err), ARM64_HAS_UAO);			\
		break;							\
	default:							\
		BUILD_BUG();						\
	}								\
	uaccess_disable_not_uao();					\
} while (0)

#define __put_user(x, ptr)						\
({									\
	int __pu_err = 0;						\
	__put_user_err((x), (ptr), __pu_err);				\
	__pu_err;							\
})

#define __put_user_error(x, ptr, err)					\
({									\
	__put_user_err((x), (ptr), (err));				\
	(void)0;							\
})

#define put_user(x, ptr)						\
({									\
	__typeof__(*(ptr)) __user *__p = (ptr);				\
	might_fault();							\
	access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ?			\
		__put_user((x), __p) :					\
		-EFAULT;						\
})

extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n);
#define raw_copy_from_user __arch_copy_from_user
extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n);
#define raw_copy_to_user __arch_copy_to_user
extern unsigned long __must_check raw_copy_in_user(void __user *to, const void __user *from, unsigned long n);
extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
#define INLINE_COPY_TO_USER
#define INLINE_COPY_FROM_USER

static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
{
	if (access_ok(VERIFY_WRITE, to, n))
		n = __clear_user(to, n);
	return n;
}

extern long strncpy_from_user(char *dest, const char __user *src, long count);

extern __must_check long strnlen_user(const char __user *str, long n);

#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
struct page;
void memcpy_page_flushcache(char *to, struct page *page, size_t offset, size_t len);
extern unsigned long __must_check __copy_user_flushcache(void *to, const void __user *from, unsigned long n);

static inline int __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)
{
	kasan_check_write(dst, size);
	return __copy_user_flushcache(dst, src, size);
}
#endif

#endif /* __ASM_UACCESS_H */