1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * arch/arm/include/asm/uaccess.h
4 */
5 #ifndef _ASMARM_UACCESS_H
6 #define _ASMARM_UACCESS_H
7
8 /*
9 * User space memory access functions
10 */
11 #include <linux/string.h>
12 #include <asm/page.h>
13 #include <asm/domain.h>
14 #include <asm/unaligned.h>
15 #include <asm/unified.h>
16 #include <asm/compiler.h>
17
18 #include <asm/extable.h>
19
20 /*
21 * These two functions allow hooking accesses to userspace to increase
22 * system integrity by ensuring that the kernel can not inadvertantly
23 * perform such accesses (eg, via list poison values) which could then
24 * be exploited for priviledge escalation.
25 */
uaccess_save_and_enable(void)26 static __always_inline unsigned int uaccess_save_and_enable(void)
27 {
28 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
29 unsigned int old_domain = get_domain();
30
31 /* Set the current domain access to permit user accesses */
32 set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
33 domain_val(DOMAIN_USER, DOMAIN_CLIENT));
34
35 return old_domain;
36 #else
37 return 0;
38 #endif
39 }
40
uaccess_restore(unsigned int flags)41 static __always_inline void uaccess_restore(unsigned int flags)
42 {
43 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
44 /* Restore the user access mask */
45 set_domain(flags);
46 #endif
47 }
48
49 /*
50 * These two are intentionally not defined anywhere - if the kernel
51 * code generates any references to them, that's a bug.
52 */
53 extern int __get_user_bad(void);
54 extern int __put_user_bad(void);
55
56 #ifdef CONFIG_MMU
57
58 /*
59 * This is a type: either unsigned long, if the argument fits into
60 * that type, or otherwise unsigned long long.
61 */
62 #define __inttype(x) \
63 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
64
65 /*
66 * Sanitise a uaccess pointer such that it becomes NULL if addr+size
67 * is above the current addr_limit.
68 */
69 #define uaccess_mask_range_ptr(ptr, size) \
70 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
__uaccess_mask_range_ptr(const void __user * ptr,size_t size)71 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
72 size_t size)
73 {
74 void __user *safe_ptr = (void __user *)ptr;
75 unsigned long tmp;
76
77 asm volatile(
78 " .syntax unified\n"
79 " sub %1, %3, #1\n"
80 " subs %1, %1, %0\n"
81 " addhs %1, %1, #1\n"
82 " subshs %1, %1, %2\n"
83 " movlo %0, #0\n"
84 : "+r" (safe_ptr), "=&r" (tmp)
85 : "r" (size), "r" (TASK_SIZE)
86 : "cc");
87
88 csdb();
89 return safe_ptr;
90 }
91
92 /*
93 * Single-value transfer routines. They automatically use the right
94 * size if we just have the right pointer type. Note that the functions
95 * which read from user space (*get_*) need to take care not to leak
96 * kernel data even if the calling code is buggy and fails to check
97 * the return value. This means zeroing out the destination variable
98 * or buffer on error. Normally this is done out of line by the
99 * fixup code, but there are a few places where it intrudes on the
100 * main code path. When we only write to user space, there is no
101 * problem.
102 */
103 extern int __get_user_1(void *);
104 extern int __get_user_2(void *);
105 extern int __get_user_4(void *);
106 extern int __get_user_32t_8(void *);
107 extern int __get_user_8(void *);
108 extern int __get_user_64t_1(void *);
109 extern int __get_user_64t_2(void *);
110 extern int __get_user_64t_4(void *);
111
112 #define __GUP_CLOBBER_1 "lr", "cc"
113 #ifdef CONFIG_CPU_USE_DOMAINS
114 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
115 #else
116 #define __GUP_CLOBBER_2 "lr", "cc"
117 #endif
118 #define __GUP_CLOBBER_4 "lr", "cc"
119 #define __GUP_CLOBBER_32t_8 "lr", "cc"
120 #define __GUP_CLOBBER_8 "lr", "cc"
121
122 #define __get_user_x(__r2, __p, __e, __l, __s) \
123 __asm__ __volatile__ ( \
124 __asmeq("%0", "r0") __asmeq("%1", "r2") \
125 __asmeq("%3", "r1") \
126 "bl __get_user_" #__s \
127 : "=&r" (__e), "=r" (__r2) \
128 : "0" (__p), "r" (__l) \
129 : __GUP_CLOBBER_##__s)
130
131 /* narrowing a double-word get into a single 32bit word register: */
132 #ifdef __ARMEB__
133 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \
134 __get_user_x(__r2, __p, __e, __l, 32t_8)
135 #else
136 #define __get_user_x_32t __get_user_x
137 #endif
138
139 /*
140 * storing result into proper least significant word of 64bit target var,
141 * different only for big endian case where 64 bit __r2 lsw is r3:
142 */
143 #ifdef __ARMEB__
144 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \
145 __asm__ __volatile__ ( \
146 __asmeq("%0", "r0") __asmeq("%1", "r2") \
147 __asmeq("%3", "r1") \
148 "bl __get_user_64t_" #__s \
149 : "=&r" (__e), "=r" (__r2) \
150 : "0" (__p), "r" (__l) \
151 : __GUP_CLOBBER_##__s)
152 #else
153 #define __get_user_x_64t __get_user_x
154 #endif
155
156
157 #define __get_user_check(x, p) \
158 ({ \
159 unsigned long __limit = TASK_SIZE - 1; \
160 register typeof(*(p)) __user *__p asm("r0") = (p); \
161 register __inttype(x) __r2 asm("r2"); \
162 register unsigned long __l asm("r1") = __limit; \
163 register int __e asm("r0"); \
164 unsigned int __ua_flags = uaccess_save_and_enable(); \
165 int __tmp_e; \
166 switch (sizeof(*(__p))) { \
167 case 1: \
168 if (sizeof((x)) >= 8) \
169 __get_user_x_64t(__r2, __p, __e, __l, 1); \
170 else \
171 __get_user_x(__r2, __p, __e, __l, 1); \
172 break; \
173 case 2: \
174 if (sizeof((x)) >= 8) \
175 __get_user_x_64t(__r2, __p, __e, __l, 2); \
176 else \
177 __get_user_x(__r2, __p, __e, __l, 2); \
178 break; \
179 case 4: \
180 if (sizeof((x)) >= 8) \
181 __get_user_x_64t(__r2, __p, __e, __l, 4); \
182 else \
183 __get_user_x(__r2, __p, __e, __l, 4); \
184 break; \
185 case 8: \
186 if (sizeof((x)) < 8) \
187 __get_user_x_32t(__r2, __p, __e, __l, 4); \
188 else \
189 __get_user_x(__r2, __p, __e, __l, 8); \
190 break; \
191 default: __e = __get_user_bad(); break; \
192 } \
193 __tmp_e = __e; \
194 uaccess_restore(__ua_flags); \
195 x = (typeof(*(p))) __r2; \
196 __tmp_e; \
197 })
198
199 #define get_user(x, p) \
200 ({ \
201 might_fault(); \
202 __get_user_check(x, p); \
203 })
204
205 extern int __put_user_1(void *, unsigned int);
206 extern int __put_user_2(void *, unsigned int);
207 extern int __put_user_4(void *, unsigned int);
208 extern int __put_user_8(void *, unsigned long long);
209
210 #define __put_user_check(__pu_val, __ptr, __err, __s) \
211 ({ \
212 unsigned long __limit = TASK_SIZE - 1; \
213 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \
214 register const void __user *__p asm("r0") = __ptr; \
215 register unsigned long __l asm("r1") = __limit; \
216 register int __e asm("r0"); \
217 __asm__ __volatile__ ( \
218 __asmeq("%0", "r0") __asmeq("%2", "r2") \
219 __asmeq("%3", "r1") \
220 "bl __put_user_" #__s \
221 : "=&r" (__e) \
222 : "0" (__p), "r" (__r2), "r" (__l) \
223 : "ip", "lr", "cc"); \
224 __err = __e; \
225 })
226
227 #else /* CONFIG_MMU */
228
229 #define get_user(x, p) __get_user(x, p)
230 #define __put_user_check __put_user_nocheck
231
232 #endif /* CONFIG_MMU */
233
234 #include <asm-generic/access_ok.h>
235
236 #ifdef CONFIG_CPU_SPECTRE
237 /*
238 * When mitigating Spectre variant 1, it is not worth fixing the non-
239 * verifying accessors, because we need to add verification of the
240 * address space there. Force these to use the standard get_user()
241 * version instead.
242 */
243 #define __get_user(x, ptr) get_user(x, ptr)
244 #else
245
246 /*
247 * The "__xxx" versions of the user access functions do not verify the
248 * address space - it must have been done previously with a separate
249 * "access_ok()" call.
250 *
251 * The "xxx_error" versions set the third argument to EFAULT if an
252 * error occurs, and leave it unchanged on success. Note that these
253 * versions are void (ie, don't return a value as such).
254 */
255 #define __get_user(x, ptr) \
256 ({ \
257 long __gu_err = 0; \
258 __get_user_err((x), (ptr), __gu_err, TUSER()); \
259 __gu_err; \
260 })
261
262 #define __get_user_err(x, ptr, err, __t) \
263 do { \
264 unsigned long __gu_addr = (unsigned long)(ptr); \
265 unsigned long __gu_val; \
266 unsigned int __ua_flags; \
267 __chk_user_ptr(ptr); \
268 might_fault(); \
269 __ua_flags = uaccess_save_and_enable(); \
270 switch (sizeof(*(ptr))) { \
271 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break; \
272 case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break; \
273 case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break; \
274 default: (__gu_val) = __get_user_bad(); \
275 } \
276 uaccess_restore(__ua_flags); \
277 (x) = (__typeof__(*(ptr)))__gu_val; \
278 } while (0)
279 #endif
280
281 #define __get_user_asm(x, addr, err, instr) \
282 __asm__ __volatile__( \
283 "1: " instr " %1, [%2], #0\n" \
284 "2:\n" \
285 " .pushsection .text.fixup,\"ax\"\n" \
286 " .align 2\n" \
287 "3: mov %0, %3\n" \
288 " mov %1, #0\n" \
289 " b 2b\n" \
290 " .popsection\n" \
291 " .pushsection __ex_table,\"a\"\n" \
292 " .align 3\n" \
293 " .long 1b, 3b\n" \
294 " .popsection" \
295 : "+r" (err), "=&r" (x) \
296 : "r" (addr), "i" (-EFAULT) \
297 : "cc")
298
299 #define __get_user_asm_byte(x, addr, err, __t) \
300 __get_user_asm(x, addr, err, "ldrb" __t)
301
302 #if __LINUX_ARM_ARCH__ >= 6
303
304 #define __get_user_asm_half(x, addr, err, __t) \
305 __get_user_asm(x, addr, err, "ldrh" __t)
306
307 #else
308
309 #ifndef __ARMEB__
310 #define __get_user_asm_half(x, __gu_addr, err, __t) \
311 ({ \
312 unsigned long __b1, __b2; \
313 __get_user_asm_byte(__b1, __gu_addr, err, __t); \
314 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \
315 (x) = __b1 | (__b2 << 8); \
316 })
317 #else
318 #define __get_user_asm_half(x, __gu_addr, err, __t) \
319 ({ \
320 unsigned long __b1, __b2; \
321 __get_user_asm_byte(__b1, __gu_addr, err, __t); \
322 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \
323 (x) = (__b1 << 8) | __b2; \
324 })
325 #endif
326
327 #endif /* __LINUX_ARM_ARCH__ >= 6 */
328
329 #define __get_user_asm_word(x, addr, err, __t) \
330 __get_user_asm(x, addr, err, "ldr" __t)
331
332 #define __put_user_switch(x, ptr, __err, __fn) \
333 do { \
334 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \
335 __typeof__(*(ptr)) __pu_val = (x); \
336 unsigned int __ua_flags; \
337 might_fault(); \
338 __ua_flags = uaccess_save_and_enable(); \
339 switch (sizeof(*(ptr))) { \
340 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \
341 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \
342 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \
343 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \
344 default: __err = __put_user_bad(); break; \
345 } \
346 uaccess_restore(__ua_flags); \
347 } while (0)
348
349 #define put_user(x, ptr) \
350 ({ \
351 int __pu_err = 0; \
352 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \
353 __pu_err; \
354 })
355
356 #ifdef CONFIG_CPU_SPECTRE
357 /*
358 * When mitigating Spectre variant 1.1, all accessors need to include
359 * verification of the address space.
360 */
361 #define __put_user(x, ptr) put_user(x, ptr)
362
363 #else
364 #define __put_user(x, ptr) \
365 ({ \
366 long __pu_err = 0; \
367 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \
368 __pu_err; \
369 })
370
371 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \
372 do { \
373 unsigned long __pu_addr = (unsigned long)__pu_ptr; \
374 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\
375 } while (0)
376
377 #define __put_user_nocheck_1 __put_user_asm_byte
378 #define __put_user_nocheck_2 __put_user_asm_half
379 #define __put_user_nocheck_4 __put_user_asm_word
380 #define __put_user_nocheck_8 __put_user_asm_dword
381
382 #endif /* !CONFIG_CPU_SPECTRE */
383
384 #define __put_user_asm(x, __pu_addr, err, instr) \
385 __asm__ __volatile__( \
386 "1: " instr " %1, [%2], #0\n" \
387 "2:\n" \
388 " .pushsection .text.fixup,\"ax\"\n" \
389 " .align 2\n" \
390 "3: mov %0, %3\n" \
391 " b 2b\n" \
392 " .popsection\n" \
393 " .pushsection __ex_table,\"a\"\n" \
394 " .align 3\n" \
395 " .long 1b, 3b\n" \
396 " .popsection" \
397 : "+r" (err) \
398 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \
399 : "cc")
400
401 #define __put_user_asm_byte(x, __pu_addr, err, __t) \
402 __put_user_asm(x, __pu_addr, err, "strb" __t)
403
404 #if __LINUX_ARM_ARCH__ >= 6
405
406 #define __put_user_asm_half(x, __pu_addr, err, __t) \
407 __put_user_asm(x, __pu_addr, err, "strh" __t)
408
409 #else
410
411 #ifndef __ARMEB__
412 #define __put_user_asm_half(x, __pu_addr, err, __t) \
413 ({ \
414 unsigned long __temp = (__force unsigned long)(x); \
415 __put_user_asm_byte(__temp, __pu_addr, err, __t); \
416 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\
417 })
418 #else
419 #define __put_user_asm_half(x, __pu_addr, err, __t) \
420 ({ \
421 unsigned long __temp = (__force unsigned long)(x); \
422 __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t); \
423 __put_user_asm_byte(__temp, __pu_addr + 1, err, __t); \
424 })
425 #endif
426
427 #endif /* __LINUX_ARM_ARCH__ >= 6 */
428
429 #define __put_user_asm_word(x, __pu_addr, err, __t) \
430 __put_user_asm(x, __pu_addr, err, "str" __t)
431
432 #ifndef __ARMEB__
433 #define __reg_oper0 "%R2"
434 #define __reg_oper1 "%Q2"
435 #else
436 #define __reg_oper0 "%Q2"
437 #define __reg_oper1 "%R2"
438 #endif
439
440 #define __put_user_asm_dword(x, __pu_addr, err, __t) \
441 __asm__ __volatile__( \
442 ARM( "1: str" __t " " __reg_oper1 ", [%1], #4\n" ) \
443 ARM( "2: str" __t " " __reg_oper0 ", [%1]\n" ) \
444 THUMB( "1: str" __t " " __reg_oper1 ", [%1]\n" ) \
445 THUMB( "2: str" __t " " __reg_oper0 ", [%1, #4]\n" ) \
446 "3:\n" \
447 " .pushsection .text.fixup,\"ax\"\n" \
448 " .align 2\n" \
449 "4: mov %0, %3\n" \
450 " b 3b\n" \
451 " .popsection\n" \
452 " .pushsection __ex_table,\"a\"\n" \
453 " .align 3\n" \
454 " .long 1b, 4b\n" \
455 " .long 2b, 4b\n" \
456 " .popsection" \
457 : "+r" (err), "+r" (__pu_addr) \
458 : "r" (x), "i" (-EFAULT) \
459 : "cc")
460
461 #define __get_kernel_nofault(dst, src, type, err_label) \
462 do { \
463 const type *__pk_ptr = (src); \
464 unsigned long __src = (unsigned long)(__pk_ptr); \
465 type __val; \
466 int __err = 0; \
467 switch (sizeof(type)) { \
468 case 1: __get_user_asm_byte(__val, __src, __err, ""); break; \
469 case 2: __get_user_asm_half(__val, __src, __err, ""); break; \
470 case 4: __get_user_asm_word(__val, __src, __err, ""); break; \
471 case 8: { \
472 u32 *__v32 = (u32*)&__val; \
473 __get_user_asm_word(__v32[0], __src, __err, ""); \
474 if (__err) \
475 break; \
476 __get_user_asm_word(__v32[1], __src+4, __err, ""); \
477 break; \
478 } \
479 default: __err = __get_user_bad(); break; \
480 } \
481 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) \
482 put_unaligned(__val, (type *)(dst)); \
483 else \
484 *(type *)(dst) = __val; /* aligned by caller */ \
485 if (__err) \
486 goto err_label; \
487 } while (0)
488
489 #define __put_kernel_nofault(dst, src, type, err_label) \
490 do { \
491 const type *__pk_ptr = (dst); \
492 unsigned long __dst = (unsigned long)__pk_ptr; \
493 int __err = 0; \
494 type __val = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) \
495 ? get_unaligned((type *)(src)) \
496 : *(type *)(src); /* aligned by caller */ \
497 switch (sizeof(type)) { \
498 case 1: __put_user_asm_byte(__val, __dst, __err, ""); break; \
499 case 2: __put_user_asm_half(__val, __dst, __err, ""); break; \
500 case 4: __put_user_asm_word(__val, __dst, __err, ""); break; \
501 case 8: __put_user_asm_dword(__val, __dst, __err, ""); break; \
502 default: __err = __put_user_bad(); break; \
503 } \
504 if (__err) \
505 goto err_label; \
506 } while (0)
507
508 #ifdef CONFIG_MMU
509 extern unsigned long __must_check
510 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
511
512 static inline unsigned long __must_check
raw_copy_from_user(void * to,const void __user * from,unsigned long n)513 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
514 {
515 unsigned int __ua_flags;
516
517 __ua_flags = uaccess_save_and_enable();
518 n = arm_copy_from_user(to, from, n);
519 uaccess_restore(__ua_flags);
520 return n;
521 }
522
523 extern unsigned long __must_check
524 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
525 extern unsigned long __must_check
526 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
527
528 static inline unsigned long __must_check
raw_copy_to_user(void __user * to,const void * from,unsigned long n)529 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
530 {
531 #ifndef CONFIG_UACCESS_WITH_MEMCPY
532 unsigned int __ua_flags;
533 __ua_flags = uaccess_save_and_enable();
534 n = arm_copy_to_user(to, from, n);
535 uaccess_restore(__ua_flags);
536 return n;
537 #else
538 return arm_copy_to_user(to, from, n);
539 #endif
540 }
541
542 extern unsigned long __must_check
543 arm_clear_user(void __user *addr, unsigned long n);
544 extern unsigned long __must_check
545 __clear_user_std(void __user *addr, unsigned long n);
546
547 static inline unsigned long __must_check
__clear_user(void __user * addr,unsigned long n)548 __clear_user(void __user *addr, unsigned long n)
549 {
550 unsigned int __ua_flags = uaccess_save_and_enable();
551 n = arm_clear_user(addr, n);
552 uaccess_restore(__ua_flags);
553 return n;
554 }
555
556 #else
557 static inline unsigned long
raw_copy_from_user(void * to,const void __user * from,unsigned long n)558 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
559 {
560 memcpy(to, (const void __force *)from, n);
561 return 0;
562 }
563 static inline unsigned long
raw_copy_to_user(void __user * to,const void * from,unsigned long n)564 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
565 {
566 memcpy((void __force *)to, from, n);
567 return 0;
568 }
569 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0)
570 #endif
571 #define INLINE_COPY_TO_USER
572 #define INLINE_COPY_FROM_USER
573
clear_user(void __user * to,unsigned long n)574 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
575 {
576 if (access_ok(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 strnlen_user(const char __user *str, long n);
585
586 #endif /* _ASMARM_UACCESS_H */
587