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/memory.h>
13 #include <asm/domain.h>
14 #include <asm/unified.h>
15 #include <asm/compiler.h>
16
17 #include <asm/extable.h>
18
19 /*
20 * These two functions allow hooking accesses to userspace to increase
21 * system integrity by ensuring that the kernel can not inadvertantly
22 * perform such accesses (eg, via list poison values) which could then
23 * be exploited for priviledge escalation.
24 */
uaccess_save_and_enable(void)25 static __always_inline unsigned int uaccess_save_and_enable(void)
26 {
27 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
28 unsigned int old_domain = get_domain();
29
30 /* Set the current domain access to permit user accesses */
31 set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
32 domain_val(DOMAIN_USER, DOMAIN_CLIENT));
33
34 return old_domain;
35 #else
36 return 0;
37 #endif
38 }
39
uaccess_restore(unsigned int flags)40 static __always_inline void uaccess_restore(unsigned int flags)
41 {
42 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
43 /* Restore the user access mask */
44 set_domain(flags);
45 #endif
46 }
47
48 /*
49 * These two are intentionally not defined anywhere - if the kernel
50 * code generates any references to them, that's a bug.
51 */
52 extern int __get_user_bad(void);
53 extern int __put_user_bad(void);
54
55 /*
56 * Note that this is actually 0x1,0000,0000
57 */
58 #define KERNEL_DS 0x00000000
59
60 #ifdef CONFIG_MMU
61
62 #define USER_DS TASK_SIZE
63 #define get_fs() (current_thread_info()->addr_limit)
64
set_fs(mm_segment_t fs)65 static inline void set_fs(mm_segment_t fs)
66 {
67 current_thread_info()->addr_limit = fs;
68
69 /*
70 * Prevent a mispredicted conditional call to set_fs from forwarding
71 * the wrong address limit to access_ok under speculation.
72 */
73 dsb(nsh);
74 isb();
75
76 modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
77 }
78
79 #define uaccess_kernel() (get_fs() == KERNEL_DS)
80
81 /*
82 * We use 33-bit arithmetic here. Success returns zero, failure returns
83 * addr_limit. We take advantage that addr_limit will be zero for KERNEL_DS,
84 * so this will always return success in that case.
85 */
86 #define __range_ok(addr, size) ({ \
87 unsigned long flag, roksum; \
88 __chk_user_ptr(addr); \
89 __asm__(".syntax unified\n" \
90 "adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \
91 : "=&r" (flag), "=&r" (roksum) \
92 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
93 : "cc"); \
94 flag; })
95
96 /*
97 * This is a type: either unsigned long, if the argument fits into
98 * that type, or otherwise unsigned long long.
99 */
100 #define __inttype(x) \
101 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
102
103 /*
104 * Sanitise a uaccess pointer such that it becomes NULL if addr+size
105 * is above the current addr_limit.
106 */
107 #define uaccess_mask_range_ptr(ptr, size) \
108 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
__uaccess_mask_range_ptr(const void __user * ptr,size_t size)109 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
110 size_t size)
111 {
112 void __user *safe_ptr = (void __user *)ptr;
113 unsigned long tmp;
114
115 asm volatile(
116 " .syntax unified\n"
117 " sub %1, %3, #1\n"
118 " subs %1, %1, %0\n"
119 " addhs %1, %1, #1\n"
120 " subshs %1, %1, %2\n"
121 " movlo %0, #0\n"
122 : "+r" (safe_ptr), "=&r" (tmp)
123 : "r" (size), "r" (current_thread_info()->addr_limit)
124 : "cc");
125
126 csdb();
127 return safe_ptr;
128 }
129
130 /*
131 * Single-value transfer routines. They automatically use the right
132 * size if we just have the right pointer type. Note that the functions
133 * which read from user space (*get_*) need to take care not to leak
134 * kernel data even if the calling code is buggy and fails to check
135 * the return value. This means zeroing out the destination variable
136 * or buffer on error. Normally this is done out of line by the
137 * fixup code, but there are a few places where it intrudes on the
138 * main code path. When we only write to user space, there is no
139 * problem.
140 */
141 extern int __get_user_1(void *);
142 extern int __get_user_2(void *);
143 extern int __get_user_4(void *);
144 extern int __get_user_32t_8(void *);
145 extern int __get_user_8(void *);
146 extern int __get_user_64t_1(void *);
147 extern int __get_user_64t_2(void *);
148 extern int __get_user_64t_4(void *);
149
150 #define __GUP_CLOBBER_1 "lr", "cc"
151 #ifdef CONFIG_CPU_USE_DOMAINS
152 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
153 #else
154 #define __GUP_CLOBBER_2 "lr", "cc"
155 #endif
156 #define __GUP_CLOBBER_4 "lr", "cc"
157 #define __GUP_CLOBBER_32t_8 "lr", "cc"
158 #define __GUP_CLOBBER_8 "lr", "cc"
159
160 #define __get_user_x(__r2, __p, __e, __l, __s) \
161 __asm__ __volatile__ ( \
162 __asmeq("%0", "r0") __asmeq("%1", "r2") \
163 __asmeq("%3", "r1") \
164 "bl __get_user_" #__s \
165 : "=&r" (__e), "=r" (__r2) \
166 : "0" (__p), "r" (__l) \
167 : __GUP_CLOBBER_##__s)
168
169 /* narrowing a double-word get into a single 32bit word register: */
170 #ifdef __ARMEB__
171 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \
172 __get_user_x(__r2, __p, __e, __l, 32t_8)
173 #else
174 #define __get_user_x_32t __get_user_x
175 #endif
176
177 /*
178 * storing result into proper least significant word of 64bit target var,
179 * different only for big endian case where 64 bit __r2 lsw is r3:
180 */
181 #ifdef __ARMEB__
182 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \
183 __asm__ __volatile__ ( \
184 __asmeq("%0", "r0") __asmeq("%1", "r2") \
185 __asmeq("%3", "r1") \
186 "bl __get_user_64t_" #__s \
187 : "=&r" (__e), "=r" (__r2) \
188 : "0" (__p), "r" (__l) \
189 : __GUP_CLOBBER_##__s)
190 #else
191 #define __get_user_x_64t __get_user_x
192 #endif
193
194
195 #define __get_user_check(x, p) \
196 ({ \
197 unsigned long __limit = current_thread_info()->addr_limit - 1; \
198 register typeof(*(p)) __user *__p asm("r0") = (p); \
199 register __inttype(x) __r2 asm("r2"); \
200 register unsigned long __l asm("r1") = __limit; \
201 register int __e asm("r0"); \
202 unsigned int __ua_flags = uaccess_save_and_enable(); \
203 switch (sizeof(*(__p))) { \
204 case 1: \
205 if (sizeof((x)) >= 8) \
206 __get_user_x_64t(__r2, __p, __e, __l, 1); \
207 else \
208 __get_user_x(__r2, __p, __e, __l, 1); \
209 break; \
210 case 2: \
211 if (sizeof((x)) >= 8) \
212 __get_user_x_64t(__r2, __p, __e, __l, 2); \
213 else \
214 __get_user_x(__r2, __p, __e, __l, 2); \
215 break; \
216 case 4: \
217 if (sizeof((x)) >= 8) \
218 __get_user_x_64t(__r2, __p, __e, __l, 4); \
219 else \
220 __get_user_x(__r2, __p, __e, __l, 4); \
221 break; \
222 case 8: \
223 if (sizeof((x)) < 8) \
224 __get_user_x_32t(__r2, __p, __e, __l, 4); \
225 else \
226 __get_user_x(__r2, __p, __e, __l, 8); \
227 break; \
228 default: __e = __get_user_bad(); break; \
229 } \
230 uaccess_restore(__ua_flags); \
231 x = (typeof(*(p))) __r2; \
232 __e; \
233 })
234
235 #define get_user(x, p) \
236 ({ \
237 might_fault(); \
238 __get_user_check(x, p); \
239 })
240
241 extern int __put_user_1(void *, unsigned int);
242 extern int __put_user_2(void *, unsigned int);
243 extern int __put_user_4(void *, unsigned int);
244 extern int __put_user_8(void *, unsigned long long);
245
246 #define __put_user_check(__pu_val, __ptr, __err, __s) \
247 ({ \
248 unsigned long __limit = current_thread_info()->addr_limit - 1; \
249 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \
250 register const void __user *__p asm("r0") = __ptr; \
251 register unsigned long __l asm("r1") = __limit; \
252 register int __e asm("r0"); \
253 __asm__ __volatile__ ( \
254 __asmeq("%0", "r0") __asmeq("%2", "r2") \
255 __asmeq("%3", "r1") \
256 "bl __put_user_" #__s \
257 : "=&r" (__e) \
258 : "0" (__p), "r" (__r2), "r" (__l) \
259 : "ip", "lr", "cc"); \
260 __err = __e; \
261 })
262
263 #else /* CONFIG_MMU */
264
265 /*
266 * uClinux has only one addr space, so has simplified address limits.
267 */
268 #define USER_DS KERNEL_DS
269
270 #define uaccess_kernel() (true)
271 #define __addr_ok(addr) ((void)(addr), 1)
272 #define __range_ok(addr, size) ((void)(addr), 0)
273 #define get_fs() (KERNEL_DS)
274
set_fs(mm_segment_t fs)275 static inline void set_fs(mm_segment_t fs)
276 {
277 }
278
279 #define get_user(x, p) __get_user(x, p)
280 #define __put_user_check __put_user_nocheck
281
282 #endif /* CONFIG_MMU */
283
284 #define access_ok(addr, size) (__range_ok(addr, size) == 0)
285
286 #define user_addr_max() \
287 (uaccess_kernel() ? ~0UL : get_fs())
288
289 #ifdef CONFIG_CPU_SPECTRE
290 /*
291 * When mitigating Spectre variant 1, it is not worth fixing the non-
292 * verifying accessors, because we need to add verification of the
293 * address space there. Force these to use the standard get_user()
294 * version instead.
295 */
296 #define __get_user(x, ptr) get_user(x, ptr)
297 #else
298
299 /*
300 * The "__xxx" versions of the user access functions do not verify the
301 * address space - it must have been done previously with a separate
302 * "access_ok()" call.
303 *
304 * The "xxx_error" versions set the third argument to EFAULT if an
305 * error occurs, and leave it unchanged on success. Note that these
306 * versions are void (ie, don't return a value as such).
307 */
308 #define __get_user(x, ptr) \
309 ({ \
310 long __gu_err = 0; \
311 __get_user_err((x), (ptr), __gu_err); \
312 __gu_err; \
313 })
314
315 #define __get_user_err(x, ptr, err) \
316 do { \
317 unsigned long __gu_addr = (unsigned long)(ptr); \
318 unsigned long __gu_val; \
319 unsigned int __ua_flags; \
320 __chk_user_ptr(ptr); \
321 might_fault(); \
322 __ua_flags = uaccess_save_and_enable(); \
323 switch (sizeof(*(ptr))) { \
324 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \
325 case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \
326 case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \
327 default: (__gu_val) = __get_user_bad(); \
328 } \
329 uaccess_restore(__ua_flags); \
330 (x) = (__typeof__(*(ptr)))__gu_val; \
331 } while (0)
332
333 #define __get_user_asm(x, addr, err, instr) \
334 __asm__ __volatile__( \
335 "1: " TUSER(instr) " %1, [%2], #0\n" \
336 "2:\n" \
337 " .pushsection .text.fixup,\"ax\"\n" \
338 " .align 2\n" \
339 "3: mov %0, %3\n" \
340 " mov %1, #0\n" \
341 " b 2b\n" \
342 " .popsection\n" \
343 " .pushsection __ex_table,\"a\"\n" \
344 " .align 3\n" \
345 " .long 1b, 3b\n" \
346 " .popsection" \
347 : "+r" (err), "=&r" (x) \
348 : "r" (addr), "i" (-EFAULT) \
349 : "cc")
350
351 #define __get_user_asm_byte(x, addr, err) \
352 __get_user_asm(x, addr, err, ldrb)
353
354 #if __LINUX_ARM_ARCH__ >= 6
355
356 #define __get_user_asm_half(x, addr, err) \
357 __get_user_asm(x, addr, err, ldrh)
358
359 #else
360
361 #ifndef __ARMEB__
362 #define __get_user_asm_half(x, __gu_addr, err) \
363 ({ \
364 unsigned long __b1, __b2; \
365 __get_user_asm_byte(__b1, __gu_addr, err); \
366 __get_user_asm_byte(__b2, __gu_addr + 1, err); \
367 (x) = __b1 | (__b2 << 8); \
368 })
369 #else
370 #define __get_user_asm_half(x, __gu_addr, err) \
371 ({ \
372 unsigned long __b1, __b2; \
373 __get_user_asm_byte(__b1, __gu_addr, err); \
374 __get_user_asm_byte(__b2, __gu_addr + 1, err); \
375 (x) = (__b1 << 8) | __b2; \
376 })
377 #endif
378
379 #endif /* __LINUX_ARM_ARCH__ >= 6 */
380
381 #define __get_user_asm_word(x, addr, err) \
382 __get_user_asm(x, addr, err, ldr)
383 #endif
384
385
386 #define __put_user_switch(x, ptr, __err, __fn) \
387 do { \
388 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \
389 __typeof__(*(ptr)) __pu_val = (x); \
390 unsigned int __ua_flags; \
391 might_fault(); \
392 __ua_flags = uaccess_save_and_enable(); \
393 switch (sizeof(*(ptr))) { \
394 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \
395 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \
396 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \
397 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \
398 default: __err = __put_user_bad(); break; \
399 } \
400 uaccess_restore(__ua_flags); \
401 } while (0)
402
403 #define put_user(x, ptr) \
404 ({ \
405 int __pu_err = 0; \
406 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \
407 __pu_err; \
408 })
409
410 #ifdef CONFIG_CPU_SPECTRE
411 /*
412 * When mitigating Spectre variant 1.1, all accessors need to include
413 * verification of the address space.
414 */
415 #define __put_user(x, ptr) put_user(x, ptr)
416
417 #else
418 #define __put_user(x, ptr) \
419 ({ \
420 long __pu_err = 0; \
421 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \
422 __pu_err; \
423 })
424
425 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \
426 do { \
427 unsigned long __pu_addr = (unsigned long)__pu_ptr; \
428 __put_user_nocheck_##__size(x, __pu_addr, __err); \
429 } while (0)
430
431 #define __put_user_nocheck_1 __put_user_asm_byte
432 #define __put_user_nocheck_2 __put_user_asm_half
433 #define __put_user_nocheck_4 __put_user_asm_word
434 #define __put_user_nocheck_8 __put_user_asm_dword
435
436 #define __put_user_asm(x, __pu_addr, err, instr) \
437 __asm__ __volatile__( \
438 "1: " TUSER(instr) " %1, [%2], #0\n" \
439 "2:\n" \
440 " .pushsection .text.fixup,\"ax\"\n" \
441 " .align 2\n" \
442 "3: mov %0, %3\n" \
443 " b 2b\n" \
444 " .popsection\n" \
445 " .pushsection __ex_table,\"a\"\n" \
446 " .align 3\n" \
447 " .long 1b, 3b\n" \
448 " .popsection" \
449 : "+r" (err) \
450 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \
451 : "cc")
452
453 #define __put_user_asm_byte(x, __pu_addr, err) \
454 __put_user_asm(x, __pu_addr, err, strb)
455
456 #if __LINUX_ARM_ARCH__ >= 6
457
458 #define __put_user_asm_half(x, __pu_addr, err) \
459 __put_user_asm(x, __pu_addr, err, strh)
460
461 #else
462
463 #ifndef __ARMEB__
464 #define __put_user_asm_half(x, __pu_addr, err) \
465 ({ \
466 unsigned long __temp = (__force unsigned long)(x); \
467 __put_user_asm_byte(__temp, __pu_addr, err); \
468 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err); \
469 })
470 #else
471 #define __put_user_asm_half(x, __pu_addr, err) \
472 ({ \
473 unsigned long __temp = (__force unsigned long)(x); \
474 __put_user_asm_byte(__temp >> 8, __pu_addr, err); \
475 __put_user_asm_byte(__temp, __pu_addr + 1, err); \
476 })
477 #endif
478
479 #endif /* __LINUX_ARM_ARCH__ >= 6 */
480
481 #define __put_user_asm_word(x, __pu_addr, err) \
482 __put_user_asm(x, __pu_addr, err, str)
483
484 #ifndef __ARMEB__
485 #define __reg_oper0 "%R2"
486 #define __reg_oper1 "%Q2"
487 #else
488 #define __reg_oper0 "%Q2"
489 #define __reg_oper1 "%R2"
490 #endif
491
492 #define __put_user_asm_dword(x, __pu_addr, err) \
493 __asm__ __volatile__( \
494 ARM( "1: " TUSER(str) " " __reg_oper1 ", [%1], #4\n" ) \
495 ARM( "2: " TUSER(str) " " __reg_oper0 ", [%1]\n" ) \
496 THUMB( "1: " TUSER(str) " " __reg_oper1 ", [%1]\n" ) \
497 THUMB( "2: " TUSER(str) " " __reg_oper0 ", [%1, #4]\n" ) \
498 "3:\n" \
499 " .pushsection .text.fixup,\"ax\"\n" \
500 " .align 2\n" \
501 "4: mov %0, %3\n" \
502 " b 3b\n" \
503 " .popsection\n" \
504 " .pushsection __ex_table,\"a\"\n" \
505 " .align 3\n" \
506 " .long 1b, 4b\n" \
507 " .long 2b, 4b\n" \
508 " .popsection" \
509 : "+r" (err), "+r" (__pu_addr) \
510 : "r" (x), "i" (-EFAULT) \
511 : "cc")
512
513 #endif /* !CONFIG_CPU_SPECTRE */
514
515 #ifdef CONFIG_MMU
516 extern unsigned long __must_check
517 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
518
519 static inline unsigned long __must_check
raw_copy_from_user(void * to,const void __user * from,unsigned long n)520 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
521 {
522 unsigned int __ua_flags;
523
524 __ua_flags = uaccess_save_and_enable();
525 n = arm_copy_from_user(to, from, n);
526 uaccess_restore(__ua_flags);
527 return n;
528 }
529
530 extern unsigned long __must_check
531 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
532 extern unsigned long __must_check
533 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
534
535 static inline unsigned long __must_check
raw_copy_to_user(void __user * to,const void * from,unsigned long n)536 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
537 {
538 #ifndef CONFIG_UACCESS_WITH_MEMCPY
539 unsigned int __ua_flags;
540 __ua_flags = uaccess_save_and_enable();
541 n = arm_copy_to_user(to, from, n);
542 uaccess_restore(__ua_flags);
543 return n;
544 #else
545 return arm_copy_to_user(to, from, n);
546 #endif
547 }
548
549 extern unsigned long __must_check
550 arm_clear_user(void __user *addr, unsigned long n);
551 extern unsigned long __must_check
552 __clear_user_std(void __user *addr, unsigned long n);
553
554 static inline unsigned long __must_check
__clear_user(void __user * addr,unsigned long n)555 __clear_user(void __user *addr, unsigned long n)
556 {
557 unsigned int __ua_flags = uaccess_save_and_enable();
558 n = arm_clear_user(addr, n);
559 uaccess_restore(__ua_flags);
560 return n;
561 }
562
563 #else
564 static inline unsigned long
raw_copy_from_user(void * to,const void __user * from,unsigned long n)565 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
566 {
567 memcpy(to, (const void __force *)from, n);
568 return 0;
569 }
570 static inline unsigned long
raw_copy_to_user(void __user * to,const void * from,unsigned long n)571 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
572 {
573 memcpy((void __force *)to, from, n);
574 return 0;
575 }
576 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0)
577 #endif
578 #define INLINE_COPY_TO_USER
579 #define INLINE_COPY_FROM_USER
580
clear_user(void __user * to,unsigned long n)581 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
582 {
583 if (access_ok(to, n))
584 n = __clear_user(to, n);
585 return n;
586 }
587
588 /* These are from lib/ code, and use __get_user() and friends */
589 extern long strncpy_from_user(char *dest, const char __user *src, long count);
590
591 extern __must_check long strnlen_user(const char __user *str, long n);
592
593 #endif /* _ASMARM_UACCESS_H */
594
