xref: /openbmc/linux/arch/arm/include/asm/uaccess.h (revision 174cd4b1)
1 /*
2  *  arch/arm/include/asm/uaccess.h
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  */
8 #ifndef _ASMARM_UACCESS_H
9 #define _ASMARM_UACCESS_H
10 
11 /*
12  * User space memory access functions
13  */
14 #include <linux/string.h>
15 #include <linux/thread_info.h>
16 #include <asm/errno.h>
17 #include <asm/memory.h>
18 #include <asm/domain.h>
19 #include <asm/unified.h>
20 #include <asm/compiler.h>
21 
22 #ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
23 #include <asm-generic/uaccess-unaligned.h>
24 #else
25 #define __get_user_unaligned __get_user
26 #define __put_user_unaligned __put_user
27 #endif
28 
29 #define VERIFY_READ 0
30 #define VERIFY_WRITE 1
31 
32 /*
33  * The exception table consists of pairs of addresses: the first is the
34  * address of an instruction that is allowed to fault, and the second is
35  * the address at which the program should continue.  No registers are
36  * modified, so it is entirely up to the continuation code to figure out
37  * what to do.
38  *
39  * All the routines below use bits of fixup code that are out of line
40  * with the main instruction path.  This means when everything is well,
41  * we don't even have to jump over them.  Further, they do not intrude
42  * on our cache or tlb entries.
43  */
44 
45 struct exception_table_entry
46 {
47 	unsigned long insn, fixup;
48 };
49 
50 extern int fixup_exception(struct pt_regs *regs);
51 
52 /*
53  * These two functions allow hooking accesses to userspace to increase
54  * system integrity by ensuring that the kernel can not inadvertantly
55  * perform such accesses (eg, via list poison values) which could then
56  * be exploited for priviledge escalation.
57  */
58 static inline unsigned int uaccess_save_and_enable(void)
59 {
60 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
61 	unsigned int old_domain = get_domain();
62 
63 	/* Set the current domain access to permit user accesses */
64 	set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
65 		   domain_val(DOMAIN_USER, DOMAIN_CLIENT));
66 
67 	return old_domain;
68 #else
69 	return 0;
70 #endif
71 }
72 
73 static inline void uaccess_restore(unsigned int flags)
74 {
75 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
76 	/* Restore the user access mask */
77 	set_domain(flags);
78 #endif
79 }
80 
81 /*
82  * These two are intentionally not defined anywhere - if the kernel
83  * code generates any references to them, that's a bug.
84  */
85 extern int __get_user_bad(void);
86 extern int __put_user_bad(void);
87 
88 /*
89  * Note that this is actually 0x1,0000,0000
90  */
91 #define KERNEL_DS	0x00000000
92 #define get_ds()	(KERNEL_DS)
93 
94 #ifdef CONFIG_MMU
95 
96 #define USER_DS		TASK_SIZE
97 #define get_fs()	(current_thread_info()->addr_limit)
98 
99 static inline void set_fs(mm_segment_t fs)
100 {
101 	current_thread_info()->addr_limit = fs;
102 	modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
103 }
104 
105 #define segment_eq(a, b)	((a) == (b))
106 
107 /* We use 33-bit arithmetic here... */
108 #define __range_ok(addr, size) ({ \
109 	unsigned long flag, roksum; \
110 	__chk_user_ptr(addr);	\
111 	__asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
112 		: "=&r" (flag), "=&r" (roksum) \
113 		: "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
114 		: "cc"); \
115 	flag; })
116 
117 /*
118  * Single-value transfer routines.  They automatically use the right
119  * size if we just have the right pointer type.  Note that the functions
120  * which read from user space (*get_*) need to take care not to leak
121  * kernel data even if the calling code is buggy and fails to check
122  * the return value.  This means zeroing out the destination variable
123  * or buffer on error.  Normally this is done out of line by the
124  * fixup code, but there are a few places where it intrudes on the
125  * main code path.  When we only write to user space, there is no
126  * problem.
127  */
128 extern int __get_user_1(void *);
129 extern int __get_user_2(void *);
130 extern int __get_user_4(void *);
131 extern int __get_user_32t_8(void *);
132 extern int __get_user_8(void *);
133 extern int __get_user_64t_1(void *);
134 extern int __get_user_64t_2(void *);
135 extern int __get_user_64t_4(void *);
136 
137 #define __GUP_CLOBBER_1	"lr", "cc"
138 #ifdef CONFIG_CPU_USE_DOMAINS
139 #define __GUP_CLOBBER_2	"ip", "lr", "cc"
140 #else
141 #define __GUP_CLOBBER_2 "lr", "cc"
142 #endif
143 #define __GUP_CLOBBER_4	"lr", "cc"
144 #define __GUP_CLOBBER_32t_8 "lr", "cc"
145 #define __GUP_CLOBBER_8	"lr", "cc"
146 
147 #define __get_user_x(__r2, __p, __e, __l, __s)				\
148 	   __asm__ __volatile__ (					\
149 		__asmeq("%0", "r0") __asmeq("%1", "r2")			\
150 		__asmeq("%3", "r1")					\
151 		"bl	__get_user_" #__s				\
152 		: "=&r" (__e), "=r" (__r2)				\
153 		: "0" (__p), "r" (__l)					\
154 		: __GUP_CLOBBER_##__s)
155 
156 /* narrowing a double-word get into a single 32bit word register: */
157 #ifdef __ARMEB__
158 #define __get_user_x_32t(__r2, __p, __e, __l, __s)			\
159 	__get_user_x(__r2, __p, __e, __l, 32t_8)
160 #else
161 #define __get_user_x_32t __get_user_x
162 #endif
163 
164 /*
165  * storing result into proper least significant word of 64bit target var,
166  * different only for big endian case where 64 bit __r2 lsw is r3:
167  */
168 #ifdef __ARMEB__
169 #define __get_user_x_64t(__r2, __p, __e, __l, __s)		        \
170 	   __asm__ __volatile__ (					\
171 		__asmeq("%0", "r0") __asmeq("%1", "r2")			\
172 		__asmeq("%3", "r1")					\
173 		"bl	__get_user_64t_" #__s				\
174 		: "=&r" (__e), "=r" (__r2)				\
175 		: "0" (__p), "r" (__l)					\
176 		: __GUP_CLOBBER_##__s)
177 #else
178 #define __get_user_x_64t __get_user_x
179 #endif
180 
181 
182 #define __get_user_check(x, p)						\
183 	({								\
184 		unsigned long __limit = current_thread_info()->addr_limit - 1; \
185 		register const typeof(*(p)) __user *__p asm("r0") = (p);\
186 		register typeof(x) __r2 asm("r2");			\
187 		register unsigned long __l asm("r1") = __limit;		\
188 		register int __e asm("r0");				\
189 		unsigned int __ua_flags = uaccess_save_and_enable();	\
190 		switch (sizeof(*(__p))) {				\
191 		case 1:							\
192 			if (sizeof((x)) >= 8)				\
193 				__get_user_x_64t(__r2, __p, __e, __l, 1); \
194 			else						\
195 				__get_user_x(__r2, __p, __e, __l, 1);	\
196 			break;						\
197 		case 2:							\
198 			if (sizeof((x)) >= 8)				\
199 				__get_user_x_64t(__r2, __p, __e, __l, 2); \
200 			else						\
201 				__get_user_x(__r2, __p, __e, __l, 2);	\
202 			break;						\
203 		case 4:							\
204 			if (sizeof((x)) >= 8)				\
205 				__get_user_x_64t(__r2, __p, __e, __l, 4); \
206 			else						\
207 				__get_user_x(__r2, __p, __e, __l, 4);	\
208 			break;						\
209 		case 8:							\
210 			if (sizeof((x)) < 8)				\
211 				__get_user_x_32t(__r2, __p, __e, __l, 4); \
212 			else						\
213 				__get_user_x(__r2, __p, __e, __l, 8);	\
214 			break;						\
215 		default: __e = __get_user_bad(); break;			\
216 		}							\
217 		uaccess_restore(__ua_flags);				\
218 		x = (typeof(*(p))) __r2;				\
219 		__e;							\
220 	})
221 
222 #define get_user(x, p)							\
223 	({								\
224 		might_fault();						\
225 		__get_user_check(x, p);					\
226 	 })
227 
228 extern int __put_user_1(void *, unsigned int);
229 extern int __put_user_2(void *, unsigned int);
230 extern int __put_user_4(void *, unsigned int);
231 extern int __put_user_8(void *, unsigned long long);
232 
233 #define __put_user_check(__pu_val, __ptr, __err, __s)			\
234 	({								\
235 		unsigned long __limit = current_thread_info()->addr_limit - 1; \
236 		register typeof(__pu_val) __r2 asm("r2") = __pu_val;	\
237 		register const void __user *__p asm("r0") = __ptr;	\
238 		register unsigned long __l asm("r1") = __limit;		\
239 		register int __e asm("r0");				\
240 		__asm__ __volatile__ (					\
241 			__asmeq("%0", "r0") __asmeq("%2", "r2")		\
242 			__asmeq("%3", "r1")				\
243 			"bl	__put_user_" #__s			\
244 			: "=&r" (__e)					\
245 			: "0" (__p), "r" (__r2), "r" (__l)		\
246 			: "ip", "lr", "cc");				\
247 		__err = __e;						\
248 	})
249 
250 #else /* CONFIG_MMU */
251 
252 /*
253  * uClinux has only one addr space, so has simplified address limits.
254  */
255 #define USER_DS			KERNEL_DS
256 
257 #define segment_eq(a, b)		(1)
258 #define __addr_ok(addr)		((void)(addr), 1)
259 #define __range_ok(addr, size)	((void)(addr), 0)
260 #define get_fs()		(KERNEL_DS)
261 
262 static inline void set_fs(mm_segment_t fs)
263 {
264 }
265 
266 #define get_user(x, p)	__get_user(x, p)
267 #define __put_user_check __put_user_nocheck
268 
269 #endif /* CONFIG_MMU */
270 
271 #define access_ok(type, addr, size)	(__range_ok(addr, size) == 0)
272 
273 #define user_addr_max() \
274 	(segment_eq(get_fs(), KERNEL_DS) ? ~0UL : get_fs())
275 
276 /*
277  * The "__xxx" versions of the user access functions do not verify the
278  * address space - it must have been done previously with a separate
279  * "access_ok()" call.
280  *
281  * The "xxx_error" versions set the third argument to EFAULT if an
282  * error occurs, and leave it unchanged on success.  Note that these
283  * versions are void (ie, don't return a value as such).
284  */
285 #define __get_user(x, ptr)						\
286 ({									\
287 	long __gu_err = 0;						\
288 	__get_user_err((x), (ptr), __gu_err);				\
289 	__gu_err;							\
290 })
291 
292 #define __get_user_error(x, ptr, err)					\
293 ({									\
294 	__get_user_err((x), (ptr), err);				\
295 	(void) 0;							\
296 })
297 
298 #define __get_user_err(x, ptr, err)					\
299 do {									\
300 	unsigned long __gu_addr = (unsigned long)(ptr);			\
301 	unsigned long __gu_val;						\
302 	unsigned int __ua_flags;					\
303 	__chk_user_ptr(ptr);						\
304 	might_fault();							\
305 	__ua_flags = uaccess_save_and_enable();				\
306 	switch (sizeof(*(ptr))) {					\
307 	case 1:	__get_user_asm_byte(__gu_val, __gu_addr, err);	break;	\
308 	case 2:	__get_user_asm_half(__gu_val, __gu_addr, err);	break;	\
309 	case 4:	__get_user_asm_word(__gu_val, __gu_addr, err);	break;	\
310 	default: (__gu_val) = __get_user_bad();				\
311 	}								\
312 	uaccess_restore(__ua_flags);					\
313 	(x) = (__typeof__(*(ptr)))__gu_val;				\
314 } while (0)
315 
316 #define __get_user_asm(x, addr, err, instr)			\
317 	__asm__ __volatile__(					\
318 	"1:	" TUSER(instr) " %1, [%2], #0\n"		\
319 	"2:\n"							\
320 	"	.pushsection .text.fixup,\"ax\"\n"		\
321 	"	.align	2\n"					\
322 	"3:	mov	%0, %3\n"				\
323 	"	mov	%1, #0\n"				\
324 	"	b	2b\n"					\
325 	"	.popsection\n"					\
326 	"	.pushsection __ex_table,\"a\"\n"		\
327 	"	.align	3\n"					\
328 	"	.long	1b, 3b\n"				\
329 	"	.popsection"					\
330 	: "+r" (err), "=&r" (x)					\
331 	: "r" (addr), "i" (-EFAULT)				\
332 	: "cc")
333 
334 #define __get_user_asm_byte(x, addr, err)			\
335 	__get_user_asm(x, addr, err, ldrb)
336 
337 #ifndef __ARMEB__
338 #define __get_user_asm_half(x, __gu_addr, err)			\
339 ({								\
340 	unsigned long __b1, __b2;				\
341 	__get_user_asm_byte(__b1, __gu_addr, err);		\
342 	__get_user_asm_byte(__b2, __gu_addr + 1, err);		\
343 	(x) = __b1 | (__b2 << 8);				\
344 })
345 #else
346 #define __get_user_asm_half(x, __gu_addr, err)			\
347 ({								\
348 	unsigned long __b1, __b2;				\
349 	__get_user_asm_byte(__b1, __gu_addr, err);		\
350 	__get_user_asm_byte(__b2, __gu_addr + 1, err);		\
351 	(x) = (__b1 << 8) | __b2;				\
352 })
353 #endif
354 
355 #define __get_user_asm_word(x, addr, err)			\
356 	__get_user_asm(x, addr, err, ldr)
357 
358 
359 #define __put_user_switch(x, ptr, __err, __fn)				\
360 	do {								\
361 		const __typeof__(*(ptr)) __user *__pu_ptr = (ptr);	\
362 		__typeof__(*(ptr)) __pu_val = (x);			\
363 		unsigned int __ua_flags;				\
364 		might_fault();						\
365 		__ua_flags = uaccess_save_and_enable();			\
366 		switch (sizeof(*(ptr))) {				\
367 		case 1: __fn(__pu_val, __pu_ptr, __err, 1); break;	\
368 		case 2:	__fn(__pu_val, __pu_ptr, __err, 2); break;	\
369 		case 4:	__fn(__pu_val, __pu_ptr, __err, 4); break;	\
370 		case 8:	__fn(__pu_val, __pu_ptr, __err, 8); break;	\
371 		default: __err = __put_user_bad(); break;		\
372 		}							\
373 		uaccess_restore(__ua_flags);				\
374 	} while (0)
375 
376 #define put_user(x, ptr)						\
377 ({									\
378 	int __pu_err = 0;						\
379 	__put_user_switch((x), (ptr), __pu_err, __put_user_check);	\
380 	__pu_err;							\
381 })
382 
383 #define __put_user(x, ptr)						\
384 ({									\
385 	long __pu_err = 0;						\
386 	__put_user_switch((x), (ptr), __pu_err, __put_user_nocheck);	\
387 	__pu_err;							\
388 })
389 
390 #define __put_user_error(x, ptr, err)					\
391 ({									\
392 	__put_user_switch((x), (ptr), (err), __put_user_nocheck);	\
393 	(void) 0;							\
394 })
395 
396 #define __put_user_nocheck(x, __pu_ptr, __err, __size)			\
397 	do {								\
398 		unsigned long __pu_addr = (unsigned long)__pu_ptr;	\
399 		__put_user_nocheck_##__size(x, __pu_addr, __err);	\
400 	} while (0)
401 
402 #define __put_user_nocheck_1 __put_user_asm_byte
403 #define __put_user_nocheck_2 __put_user_asm_half
404 #define __put_user_nocheck_4 __put_user_asm_word
405 #define __put_user_nocheck_8 __put_user_asm_dword
406 
407 #define __put_user_asm(x, __pu_addr, err, instr)		\
408 	__asm__ __volatile__(					\
409 	"1:	" TUSER(instr) " %1, [%2], #0\n"		\
410 	"2:\n"							\
411 	"	.pushsection .text.fixup,\"ax\"\n"		\
412 	"	.align	2\n"					\
413 	"3:	mov	%0, %3\n"				\
414 	"	b	2b\n"					\
415 	"	.popsection\n"					\
416 	"	.pushsection __ex_table,\"a\"\n"		\
417 	"	.align	3\n"					\
418 	"	.long	1b, 3b\n"				\
419 	"	.popsection"					\
420 	: "+r" (err)						\
421 	: "r" (x), "r" (__pu_addr), "i" (-EFAULT)		\
422 	: "cc")
423 
424 #define __put_user_asm_byte(x, __pu_addr, err)			\
425 	__put_user_asm(x, __pu_addr, err, strb)
426 
427 #ifndef __ARMEB__
428 #define __put_user_asm_half(x, __pu_addr, err)			\
429 ({								\
430 	unsigned long __temp = (__force unsigned long)(x);	\
431 	__put_user_asm_byte(__temp, __pu_addr, err);		\
432 	__put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);	\
433 })
434 #else
435 #define __put_user_asm_half(x, __pu_addr, err)			\
436 ({								\
437 	unsigned long __temp = (__force unsigned long)(x);	\
438 	__put_user_asm_byte(__temp >> 8, __pu_addr, err);	\
439 	__put_user_asm_byte(__temp, __pu_addr + 1, err);	\
440 })
441 #endif
442 
443 #define __put_user_asm_word(x, __pu_addr, err)			\
444 	__put_user_asm(x, __pu_addr, err, str)
445 
446 #ifndef __ARMEB__
447 #define	__reg_oper0	"%R2"
448 #define	__reg_oper1	"%Q2"
449 #else
450 #define	__reg_oper0	"%Q2"
451 #define	__reg_oper1	"%R2"
452 #endif
453 
454 #define __put_user_asm_dword(x, __pu_addr, err)			\
455 	__asm__ __volatile__(					\
456  ARM(	"1:	" TUSER(str) "	" __reg_oper1 ", [%1], #4\n"	) \
457  ARM(	"2:	" TUSER(str) "	" __reg_oper0 ", [%1]\n"	) \
458  THUMB(	"1:	" TUSER(str) "	" __reg_oper1 ", [%1]\n"	) \
459  THUMB(	"2:	" TUSER(str) "	" __reg_oper0 ", [%1, #4]\n"	) \
460 	"3:\n"							\
461 	"	.pushsection .text.fixup,\"ax\"\n"		\
462 	"	.align	2\n"					\
463 	"4:	mov	%0, %3\n"				\
464 	"	b	3b\n"					\
465 	"	.popsection\n"					\
466 	"	.pushsection __ex_table,\"a\"\n"		\
467 	"	.align	3\n"					\
468 	"	.long	1b, 4b\n"				\
469 	"	.long	2b, 4b\n"				\
470 	"	.popsection"					\
471 	: "+r" (err), "+r" (__pu_addr)				\
472 	: "r" (x), "i" (-EFAULT)				\
473 	: "cc")
474 
475 
476 #ifdef CONFIG_MMU
477 extern unsigned long __must_check
478 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
479 
480 static inline unsigned long __must_check
481 __arch_copy_from_user(void *to, const void __user *from, unsigned long n)
482 {
483 	unsigned int __ua_flags;
484 
485 	__ua_flags = uaccess_save_and_enable();
486 	n = arm_copy_from_user(to, from, n);
487 	uaccess_restore(__ua_flags);
488 	return n;
489 }
490 
491 extern unsigned long __must_check
492 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
493 extern unsigned long __must_check
494 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
495 
496 static inline unsigned long __must_check
497 __arch_copy_to_user(void __user *to, const void *from, unsigned long n)
498 {
499 #ifndef CONFIG_UACCESS_WITH_MEMCPY
500 	unsigned int __ua_flags;
501 	__ua_flags = uaccess_save_and_enable();
502 	n = arm_copy_to_user(to, from, n);
503 	uaccess_restore(__ua_flags);
504 	return n;
505 #else
506 	return arm_copy_to_user(to, from, n);
507 #endif
508 }
509 
510 extern unsigned long __must_check
511 arm_clear_user(void __user *addr, unsigned long n);
512 extern unsigned long __must_check
513 __clear_user_std(void __user *addr, unsigned long n);
514 
515 static inline unsigned long __must_check
516 __clear_user(void __user *addr, unsigned long n)
517 {
518 	unsigned int __ua_flags = uaccess_save_and_enable();
519 	n = arm_clear_user(addr, n);
520 	uaccess_restore(__ua_flags);
521 	return n;
522 }
523 
524 #else
525 #define __arch_copy_from_user(to, from, n)	\
526 					(memcpy(to, (void __force *)from, n), 0)
527 #define __arch_copy_to_user(to, from, n)	\
528 					(memcpy((void __force *)to, from, n), 0)
529 #define __clear_user(addr, n)		(memset((void __force *)addr, 0, n), 0)
530 #endif
531 
532 static inline unsigned long __must_check
533 __copy_from_user(void *to, const void __user *from, unsigned long n)
534 {
535 	check_object_size(to, n, false);
536 	return __arch_copy_from_user(to, from, n);
537 }
538 
539 static inline unsigned long __must_check
540 copy_from_user(void *to, const void __user *from, unsigned long n)
541 {
542 	unsigned long res = n;
543 
544 	check_object_size(to, n, false);
545 
546 	if (likely(access_ok(VERIFY_READ, from, n)))
547 		res = __arch_copy_from_user(to, from, n);
548 	if (unlikely(res))
549 		memset(to + (n - res), 0, res);
550 	return res;
551 }
552 
553 static inline unsigned long __must_check
554 __copy_to_user(void __user *to, const void *from, unsigned long n)
555 {
556 	check_object_size(from, n, true);
557 
558 	return __arch_copy_to_user(to, from, n);
559 }
560 
561 static inline unsigned long __must_check
562 copy_to_user(void __user *to, const void *from, unsigned long n)
563 {
564 	check_object_size(from, n, true);
565 
566 	if (access_ok(VERIFY_WRITE, to, n))
567 		n = __arch_copy_to_user(to, from, n);
568 	return n;
569 }
570 
571 #define __copy_to_user_inatomic __copy_to_user
572 #define __copy_from_user_inatomic __copy_from_user
573 
574 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
575 {
576 	if (access_ok(VERIFY_WRITE, to, n))
577 		n = __clear_user(to, n);
578 	return n;
579 }
580 
581 /* These are from lib/ code, and use __get_user() and friends */
582 extern long strncpy_from_user(char *dest, const char __user *src, long count);
583 
584 extern __must_check long strlen_user(const char __user *str);
585 extern __must_check long strnlen_user(const char __user *str, long n);
586 
587 #endif /* _ASMARM_UACCESS_H */
588