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