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/kernel.h>
12 #include <linux/string.h>
13 #include <asm/page.h>
14 #include <asm/domain.h>
15 #include <asm/unaligned.h>
16 #include <asm/unified.h>
17 #include <asm/pgtable.h>
18 #include <asm/proc-fns.h>
19 #include <asm/compiler.h>
20
21 #include <asm/extable.h>
22
23 /*
24 * These two functions allow hooking accesses to userspace to increase
25 * system integrity by ensuring that the kernel can not inadvertantly
26 * perform such accesses (eg, via list poison values) which could then
27 * be exploited for priviledge escalation.
28 */
29 #if defined(CONFIG_CPU_SW_DOMAIN_PAN)
30
31 static __always_inline unsigned int uaccess_save_and_enable(void)
32 {
33 unsigned int old_domain = get_domain();
34
35 /* Set the current domain access to permit user accesses */
36 set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
37 domain_val(DOMAIN_USER, DOMAIN_CLIENT));
38
39 return old_domain;
40 }
41
42 static __always_inline void uaccess_restore(unsigned int flags)
43 {
44 /* Restore the user access mask */
45 set_domain(flags);
46 }
47
48 #elif defined(CONFIG_CPU_TTBR0_PAN)
49
50 static __always_inline unsigned int uaccess_save_and_enable(void)
51 {
52 unsigned int old_ttbcr = cpu_get_ttbcr();
53
54 /*
55 * Enable TTBR0 page table walks (T0SZ = 0, EDP0 = 0) and ASID from
56 * TTBR0 (A1 = 0).
57 */
58 cpu_set_ttbcr(old_ttbcr & ~(TTBCR_A1 | TTBCR_EPD0 | TTBCR_T0SZ_MASK));
59 isb();
60
61 return old_ttbcr;
62 }
63
64 static inline void uaccess_restore(unsigned int flags)
65 {
66 cpu_set_ttbcr(flags);
67 isb();
68 }
69
70 #else
71
72 static inline unsigned int uaccess_save_and_enable(void)
73 {
74 return 0;
75 }
76
77 static inline void uaccess_restore(unsigned int flags)
78 {
79 }
80
81 #endif
82
83 /*
84 * These two are intentionally not defined anywhere - if the kernel
85 * code generates any references to them, that's a bug.
86 */
87 extern int __get_user_bad(void);
88 extern int __put_user_bad(void);
89
90 #ifdef CONFIG_MMU
91
92 /*
93 * This is a type: either unsigned long, if the argument fits into
94 * that type, or otherwise unsigned long long.
95 */
96 #define __inttype(x) \
97 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
98
99 /*
100 * Sanitise a uaccess pointer such that it becomes NULL if addr+size
101 * is above the current addr_limit.
102 */
103 #define uaccess_mask_range_ptr(ptr, size) \
104 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
105 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
106 size_t size)
107 {
108 void __user *safe_ptr = (void __user *)ptr;
109 unsigned long tmp;
110
111 asm volatile(
112 " .syntax unified\n"
113 " sub %1, %3, #1\n"
114 " subs %1, %1, %0\n"
115 " addhs %1, %1, #1\n"
116 " subshs %1, %1, %2\n"
117 " movlo %0, #0\n"
118 : "+r" (safe_ptr), "=&r" (tmp)
119 : "r" (size), "r" (TASK_SIZE)
120 : "cc");
121
122 csdb();
123 return safe_ptr;
124 }
125
126 /*
127 * Single-value transfer routines. They automatically use the right
128 * size if we just have the right pointer type. Note that the functions
129 * which read from user space (*get_*) need to take care not to leak
130 * kernel data even if the calling code is buggy and fails to check
131 * the return value. This means zeroing out the destination variable
132 * or buffer on error. Normally this is done out of line by the
133 * fixup code, but there are a few places where it intrudes on the
134 * main code path. When we only write to user space, there is no
135 * problem.
136 */
137 extern int __get_user_1(void *);
138 extern int __get_user_2(void *);
139 extern int __get_user_4(void *);
140 extern int __get_user_32t_8(void *);
141 extern int __get_user_8(void *);
142 extern int __get_user_64t_1(void *);
143 extern int __get_user_64t_2(void *);
144 extern int __get_user_64t_4(void *);
145
146 #define __get_user_x(__r2, __p, __e, __l, __s) \
147 __asm__ __volatile__ ( \
148 __asmeq("%0", "r0") __asmeq("%1", "r2") \
149 __asmeq("%3", "r1") \
150 "bl __get_user_" #__s \
151 : "=&r" (__e), "=r" (__r2) \
152 : "" (__p), "r" (__l) \
153 : "ip", "lr", "cc")
154
155 /* narrowing a double-word get into a single 32bit word register: */
156 #ifdef __ARMEB__
157 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \
158 __get_user_x(__r2, __p, __e, __l, 32t_8)
159 #else
160 #define __get_user_x_32t __get_user_x
161 #endif
162
163 /*
164 * storing result into proper least significant word of 64bit target var,
165 * different only for big endian case where 64 bit __r2 lsw is r3:
166 */
167 #ifdef __ARMEB__
168 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \
169 __asm__ __volatile__ ( \
170 __asmeq("%0", "r0") __asmeq("%1", "r2") \
171 __asmeq("%3", "r1") \
172 "bl __get_user_64t_" #__s \
173 : "=&r" (__e), "=r" (__r2) \
174 : "" (__p), "r" (__l) \
175 : "ip", "lr", "cc")
176 #else
177 #define __get_user_x_64t __get_user_x
178 #endif
179
180
181 #define __get_user_check(x, p) \
182 ({ \
183 unsigned long __limit = TASK_SIZE - 1; \
184 register typeof(*(p)) __user *__p asm("r0") = (p); \
185 register __inttype(x) __r2 asm("r2"); \
186 register unsigned long __l asm("r1") = __limit; \
187 register int __e asm("r0"); \
188 unsigned int __ua_flags = uaccess_save_and_enable(); \
189 int __tmp_e; \
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 __tmp_e = __e; \
218 uaccess_restore(__ua_flags); \
219 x = (typeof(*(p))) __r2; \
220 __tmp_e; \
221 })
222
223 #define get_user(x, p) \
224 ({ \
225 might_fault(); \
226 __get_user_check(x, p); \
227 })
228
229 extern int __put_user_1(void *, unsigned int);
230 extern int __put_user_2(void *, unsigned int);
231 extern int __put_user_4(void *, unsigned int);
232 extern int __put_user_8(void *, unsigned long long);
233
234 #define __put_user_check(__pu_val, __ptr, __err, __s) \
235 ({ \
236 unsigned long __limit = TASK_SIZE - 1; \
237 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \
238 register const void __user *__p asm("r0") = __ptr; \
239 register unsigned long __l asm("r1") = __limit; \
240 register int __e asm("r0"); \
241 __asm__ __volatile__ ( \
242 __asmeq("%0", "r0") __asmeq("%2", "r2") \
243 __asmeq("%3", "r1") \
244 "bl __put_user_" #__s \
245 : "=&r" (__e) \
246 : "" (__p), "r" (__r2), "r" (__l) \
247 : "ip", "lr", "cc"); \
248 __err = __e; \
249 })
250
251 #else /* CONFIG_MMU */
252
253 #define get_user(x, p) __get_user(x, p)
254 #define __put_user_check __put_user_nocheck
255
256 #endif /* CONFIG_MMU */
257
258 #include <asm-generic/access_ok.h>
259
260 #ifdef CONFIG_CPU_SPECTRE
261 /*
262 * When mitigating Spectre variant 1, it is not worth fixing the non-
263 * verifying accessors, because we need to add verification of the
264 * address space there. Force these to use the standard get_user()
265 * version instead.
266 */
267 #define __get_user(x, ptr) get_user(x, ptr)
268 #else
269
270 /*
271 * The "__xxx" versions of the user access functions do not verify the
272 * address space - it must have been done previously with a separate
273 * "access_ok()" call.
274 *
275 * The "xxx_error" versions set the third argument to EFAULT if an
276 * error occurs, and leave it unchanged on success. Note that these
277 * versions are void (ie, don't return a value as such).
278 */
279 #define __get_user(x, ptr) \
280 ({ \
281 long __gu_err = 0; \
282 __get_user_err((x), (ptr), __gu_err, TUSER()); \
283 __gu_err; \
284 })
285
286 #define __get_user_err(x, ptr, err, __t) \
287 do { \
288 unsigned long __gu_addr = (unsigned long)(ptr); \
289 unsigned long __gu_val; \
290 unsigned int __ua_flags; \
291 __chk_user_ptr(ptr); \
292 might_fault(); \
293 __ua_flags = uaccess_save_and_enable(); \
294 switch (sizeof(*(ptr))) { \
295 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break; \
296 case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break; \
297 case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break; \
298 default: (__gu_val) = __get_user_bad(); \
299 } \
300 uaccess_restore(__ua_flags); \
301 (x) = (__typeof__(*(ptr)))__gu_val; \
302 } while (0)
303 #endif
304
305 #define __get_user_asm(x, addr, err, instr) \
306 __asm__ __volatile__( \
307 "1: " instr " %1, [%2], #0\n" \
308 "2:\n" \
309 " .pushsection .text.fixup,\"ax\"\n" \
310 " .align 2\n" \
311 "3: mov %0, %3\n" \
312 " mov %1, #0\n" \
313 " b 2b\n" \
314 " .popsection\n" \
315 " .pushsection __ex_table,\"a\"\n" \
316 " .align 3\n" \
317 " .long 1b, 3b\n" \
318 " .popsection" \
319 : "+r" (err), "=&r" (x) \
320 : "r" (addr), "i" (-EFAULT) \
321 : "cc")
322
323 #define __get_user_asm_byte(x, addr, err, __t) \
324 __get_user_asm(x, addr, err, "ldrb" __t)
325
326 #if __LINUX_ARM_ARCH__ >= 6
327
328 #define __get_user_asm_half(x, addr, err, __t) \
329 __get_user_asm(x, addr, err, "ldrh" __t)
330
331 #else
332
333 #ifndef __ARMEB__
334 #define __get_user_asm_half(x, __gu_addr, err, __t) \
335 ({ \
336 unsigned long __b1, __b2; \
337 __get_user_asm_byte(__b1, __gu_addr, err, __t); \
338 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \
339 (x) = __b1 | (__b2 << 8); \
340 })
341 #else
342 #define __get_user_asm_half(x, __gu_addr, err, __t) \
343 ({ \
344 unsigned long __b1, __b2; \
345 __get_user_asm_byte(__b1, __gu_addr, err, __t); \
346 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \
347 (x) = (__b1 << 8) | __b2; \
348 })
349 #endif
350
351 #endif /* __LINUX_ARM_ARCH__ >= 6 */
352
353 #define __get_user_asm_word(x, addr, err, __t) \
354 __get_user_asm(x, addr, err, "ldr" __t)
355
356 #define __put_user_switch(x, ptr, __err, __fn) \
357 do { \
358 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \
359 __typeof__(*(ptr)) __pu_val = (x); \
360 unsigned int __ua_flags; \
361 might_fault(); \
362 __ua_flags = uaccess_save_and_enable(); \
363 switch (sizeof(*(ptr))) { \
364 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \
365 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \
366 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \
367 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \
368 default: __err = __put_user_bad(); break; \
369 } \
370 uaccess_restore(__ua_flags); \
371 } while (0)
372
373 #define put_user(x, ptr) \
374 ({ \
375 int __pu_err = 0; \
376 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \
377 __pu_err; \
378 })
379
380 #ifdef CONFIG_CPU_SPECTRE
381 /*
382 * When mitigating Spectre variant 1.1, all accessors need to include
383 * verification of the address space.
384 */
385 #define __put_user(x, ptr) put_user(x, ptr)
386
387 #else
388 #define __put_user(x, ptr) \
389 ({ \
390 long __pu_err = 0; \
391 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \
392 __pu_err; \
393 })
394
395 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \
396 do { \
397 unsigned long __pu_addr = (unsigned long)__pu_ptr; \
398 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\
399 } while (0)
400
401 #define __put_user_nocheck_1 __put_user_asm_byte
402 #define __put_user_nocheck_2 __put_user_asm_half
403 #define __put_user_nocheck_4 __put_user_asm_word
404 #define __put_user_nocheck_8 __put_user_asm_dword
405
406 #endif /* !CONFIG_CPU_SPECTRE */
407
408 #define __put_user_asm(x, __pu_addr, err, instr) \
409 __asm__ __volatile__( \
410 "1: " instr " %1, [%2], #0\n" \
411 "2:\n" \
412 " .pushsection .text.fixup,\"ax\"\n" \
413 " .align 2\n" \
414 "3: mov %0, %3\n" \
415 " b 2b\n" \
416 " .popsection\n" \
417 " .pushsection __ex_table,\"a\"\n" \
418 " .align 3\n" \
419 " .long 1b, 3b\n" \
420 " .popsection" \
421 : "+r" (err) \
422 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \
423 : "cc")
424
425 #define __put_user_asm_byte(x, __pu_addr, err, __t) \
426 __put_user_asm(x, __pu_addr, err, "strb" __t)
427
428 #if __LINUX_ARM_ARCH__ >= 6
429
430 #define __put_user_asm_half(x, __pu_addr, err, __t) \
431 __put_user_asm(x, __pu_addr, err, "strh" __t)
432
433 #else
434
435 #ifndef __ARMEB__
436 #define __put_user_asm_half(x, __pu_addr, err, __t) \
437 ({ \
438 unsigned long __temp = (__force unsigned long)(x); \
439 __put_user_asm_byte(__temp, __pu_addr, err, __t); \
440 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\
441 })
442 #else
443 #define __put_user_asm_half(x, __pu_addr, err, __t) \
444 ({ \
445 unsigned long __temp = (__force unsigned long)(x); \
446 __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t); \
447 __put_user_asm_byte(__temp, __pu_addr + 1, err, __t); \
448 })
449 #endif
450
451 #endif /* __LINUX_ARM_ARCH__ >= 6 */
452
453 #define __put_user_asm_word(x, __pu_addr, err, __t) \
454 __put_user_asm(x, __pu_addr, err, "str" __t)
455
456 #ifndef __ARMEB__
457 #define __reg_oper0 "%R2"
458 #define __reg_oper1 "%Q2"
459 #else
460 #define __reg_oper0 "%Q2"
461 #define __reg_oper1 "%R2"
462 #endif
463
464 #define __put_user_asm_dword(x, __pu_addr, err, __t) \
465 __asm__ __volatile__( \
466 ARM( "1: str" __t " " __reg_oper1 ", [%1], #4\n" ) \
467 ARM( "2: str" __t " " __reg_oper0 ", [%1]\n" ) \
468 THUMB( "1: str" __t " " __reg_oper1 ", [%1]\n" ) \
469 THUMB( "2: str" __t " " __reg_oper0 ", [%1, #4]\n" ) \
470 "3:\n" \
471 " .pushsection .text.fixup,\"ax\"\n" \
472 " .align 2\n" \
473 "4: mov %0, %3\n" \
474 " b 3b\n" \
475 " .popsection\n" \
476 " .pushsection __ex_table,\"a\"\n" \
477 " .align 3\n" \
478 " .long 1b, 4b\n" \
479 " .long 2b, 4b\n" \
480 " .popsection" \
481 : "+r" (err), "+r" (__pu_addr) \
482 : "r" (x), "i" (-EFAULT) \
483 : "cc")
484
485 #define __get_kernel_nofault(dst, src, type, err_label) \
486 do { \
487 const type *__pk_ptr = (src); \
488 unsigned long __src = (unsigned long)(__pk_ptr); \
489 type __val; \
490 int __err = 0; \
491 switch (sizeof(type)) { \
492 case 1: __get_user_asm_byte(__val, __src, __err, ""); break; \
493 case 2: __get_user_asm_half(__val, __src, __err, ""); break; \
494 case 4: __get_user_asm_word(__val, __src, __err, ""); break; \
495 case 8: { \
496 u32 *__v32 = (u32*)&__val; \
497 __get_user_asm_word(__v32[0], __src, __err, ""); \
498 if (__err) \
499 break; \
500 __get_user_asm_word(__v32[1], __src+4, __err, ""); \
501 break; \
502 } \
503 default: __err = __get_user_bad(); break; \
504 } \
505 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) \
506 put_unaligned(__val, (type *)(dst)); \
507 else \
508 *(type *)(dst) = __val; /* aligned by caller */ \
509 if (__err) \
510 goto err_label; \
511 } while (0)
512
513 #define __put_kernel_nofault(dst, src, type, err_label) \
514 do { \
515 const type *__pk_ptr = (dst); \
516 unsigned long __dst = (unsigned long)__pk_ptr; \
517 int __err = 0; \
518 type __val = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) \
519 ? get_unaligned((type *)(src)) \
520 : *(type *)(src); /* aligned by caller */ \
521 switch (sizeof(type)) { \
522 case 1: __put_user_asm_byte(__val, __dst, __err, ""); break; \
523 case 2: __put_user_asm_half(__val, __dst, __err, ""); break; \
524 case 4: __put_user_asm_word(__val, __dst, __err, ""); break; \
525 case 8: __put_user_asm_dword(__val, __dst, __err, ""); break; \
526 default: __err = __put_user_bad(); break; \
527 } \
528 if (__err) \
529 goto err_label; \
530 } while (0)
531
532 #ifdef CONFIG_MMU
533 extern unsigned long __must_check
534 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
535
536 static inline unsigned long __must_check
537 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
538 {
539 unsigned int __ua_flags;
540
541 __ua_flags = uaccess_save_and_enable();
542 n = arm_copy_from_user(to, from, n);
543 uaccess_restore(__ua_flags);
544 return n;
545 }
546
547 extern unsigned long __must_check
548 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
549 extern unsigned long __must_check
550 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
551
552 static inline unsigned long __must_check
553 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
554 {
555 #ifndef CONFIG_UACCESS_WITH_MEMCPY
556 unsigned int __ua_flags;
557 __ua_flags = uaccess_save_and_enable();
558 n = arm_copy_to_user(to, from, n);
559 uaccess_restore(__ua_flags);
560 return n;
561 #else
562 return arm_copy_to_user(to, from, n);
563 #endif
564 }
565
566 extern unsigned long __must_check
567 arm_clear_user(void __user *addr, unsigned long n);
568 extern unsigned long __must_check
569 __clear_user_std(void __user *addr, unsigned long n);
570
571 static inline unsigned long __must_check
572 __clear_user(void __user *addr, unsigned long n)
573 {
574 unsigned int __ua_flags = uaccess_save_and_enable();
575 n = arm_clear_user(addr, n);
576 uaccess_restore(__ua_flags);
577 return n;
578 }
579
580 #else
581 static inline unsigned long
582 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
583 {
584 memcpy(to, (const void __force *)from, n);
585 return 0;
586 }
587 static inline unsigned long
588 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
589 {
590 memcpy((void __force *)to, from, n);
591 return 0;
592 }
593 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0)
594 #endif
595 #define INLINE_COPY_TO_USER
596 #define INLINE_COPY_FROM_USER
597
598 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
599 {
600 if (access_ok(to, n))
601 n = __clear_user(to, n);
602 return n;
603 }
604
605 /* These are from lib/ code, and use __get_user() and friends */
606 extern long strncpy_from_user(char *dest, const char __user *src, long count);
607
608 extern __must_check long strnlen_user(const char __user *str, long n);
609
610 #endif /* _ASMARM_UACCESS_H */
611
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