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/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 * We use 33-bit arithmetic here. Success returns zero, failure returns
60 * addr_limit. We take advantage that addr_limit will be zero for KERNEL_DS,
61 * so this will always return success in that case.
62 */
63 #define __range_ok(addr, size) ({ \
64 unsigned long flag, roksum; \
65 __chk_user_ptr(addr); \
66 __asm__(".syntax unified\n" \
67 "adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \
68 : "=&r" (flag), "=&r" (roksum) \
69 : "r" (addr), "Ir" (size), "0" (TASK_SIZE) \
70 : "cc"); \
71 flag; })
72
73 /*
74 * This is a type: either unsigned long, if the argument fits into
75 * that type, or otherwise unsigned long long.
76 */
77 #define __inttype(x) \
78 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
79
80 /*
81 * Sanitise a uaccess pointer such that it becomes NULL if addr+size
82 * is above the current addr_limit.
83 */
84 #define uaccess_mask_range_ptr(ptr, size) \
85 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
__uaccess_mask_range_ptr(const void __user * ptr,size_t size)86 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
87 size_t size)
88 {
89 void __user *safe_ptr = (void __user *)ptr;
90 unsigned long tmp;
91
92 asm volatile(
93 " .syntax unified\n"
94 " sub %1, %3, #1\n"
95 " subs %1, %1, %0\n"
96 " addhs %1, %1, #1\n"
97 " subshs %1, %1, %2\n"
98 " movlo %0, #0\n"
99 : "+r" (safe_ptr), "=&r" (tmp)
100 : "r" (size), "r" (TASK_SIZE)
101 : "cc");
102
103 csdb();
104 return safe_ptr;
105 }
106
107 /*
108 * Single-value transfer routines. They automatically use the right
109 * size if we just have the right pointer type. Note that the functions
110 * which read from user space (*get_*) need to take care not to leak
111 * kernel data even if the calling code is buggy and fails to check
112 * the return value. This means zeroing out the destination variable
113 * or buffer on error. Normally this is done out of line by the
114 * fixup code, but there are a few places where it intrudes on the
115 * main code path. When we only write to user space, there is no
116 * problem.
117 */
118 extern int __get_user_1(void *);
119 extern int __get_user_2(void *);
120 extern int __get_user_4(void *);
121 extern int __get_user_32t_8(void *);
122 extern int __get_user_8(void *);
123 extern int __get_user_64t_1(void *);
124 extern int __get_user_64t_2(void *);
125 extern int __get_user_64t_4(void *);
126
127 #define __GUP_CLOBBER_1 "lr", "cc"
128 #ifdef CONFIG_CPU_USE_DOMAINS
129 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
130 #else
131 #define __GUP_CLOBBER_2 "lr", "cc"
132 #endif
133 #define __GUP_CLOBBER_4 "lr", "cc"
134 #define __GUP_CLOBBER_32t_8 "lr", "cc"
135 #define __GUP_CLOBBER_8 "lr", "cc"
136
137 #define __get_user_x(__r2, __p, __e, __l, __s) \
138 __asm__ __volatile__ ( \
139 __asmeq("%0", "r0") __asmeq("%1", "r2") \
140 __asmeq("%3", "r1") \
141 "bl __get_user_" #__s \
142 : "=&r" (__e), "=r" (__r2) \
143 : "0" (__p), "r" (__l) \
144 : __GUP_CLOBBER_##__s)
145
146 /* narrowing a double-word get into a single 32bit word register: */
147 #ifdef __ARMEB__
148 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \
149 __get_user_x(__r2, __p, __e, __l, 32t_8)
150 #else
151 #define __get_user_x_32t __get_user_x
152 #endif
153
154 /*
155 * storing result into proper least significant word of 64bit target var,
156 * different only for big endian case where 64 bit __r2 lsw is r3:
157 */
158 #ifdef __ARMEB__
159 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \
160 __asm__ __volatile__ ( \
161 __asmeq("%0", "r0") __asmeq("%1", "r2") \
162 __asmeq("%3", "r1") \
163 "bl __get_user_64t_" #__s \
164 : "=&r" (__e), "=r" (__r2) \
165 : "0" (__p), "r" (__l) \
166 : __GUP_CLOBBER_##__s)
167 #else
168 #define __get_user_x_64t __get_user_x
169 #endif
170
171
172 #define __get_user_check(x, p) \
173 ({ \
174 unsigned long __limit = TASK_SIZE - 1; \
175 register typeof(*(p)) __user *__p asm("r0") = (p); \
176 register __inttype(x) __r2 asm("r2"); \
177 register unsigned long __l asm("r1") = __limit; \
178 register int __e asm("r0"); \
179 unsigned int __ua_flags = uaccess_save_and_enable(); \
180 int __tmp_e; \
181 switch (sizeof(*(__p))) { \
182 case 1: \
183 if (sizeof((x)) >= 8) \
184 __get_user_x_64t(__r2, __p, __e, __l, 1); \
185 else \
186 __get_user_x(__r2, __p, __e, __l, 1); \
187 break; \
188 case 2: \
189 if (sizeof((x)) >= 8) \
190 __get_user_x_64t(__r2, __p, __e, __l, 2); \
191 else \
192 __get_user_x(__r2, __p, __e, __l, 2); \
193 break; \
194 case 4: \
195 if (sizeof((x)) >= 8) \
196 __get_user_x_64t(__r2, __p, __e, __l, 4); \
197 else \
198 __get_user_x(__r2, __p, __e, __l, 4); \
199 break; \
200 case 8: \
201 if (sizeof((x)) < 8) \
202 __get_user_x_32t(__r2, __p, __e, __l, 4); \
203 else \
204 __get_user_x(__r2, __p, __e, __l, 8); \
205 break; \
206 default: __e = __get_user_bad(); break; \
207 } \
208 __tmp_e = __e; \
209 uaccess_restore(__ua_flags); \
210 x = (typeof(*(p))) __r2; \
211 __tmp_e; \
212 })
213
214 #define get_user(x, p) \
215 ({ \
216 might_fault(); \
217 __get_user_check(x, p); \
218 })
219
220 extern int __put_user_1(void *, unsigned int);
221 extern int __put_user_2(void *, unsigned int);
222 extern int __put_user_4(void *, unsigned int);
223 extern int __put_user_8(void *, unsigned long long);
224
225 #define __put_user_check(__pu_val, __ptr, __err, __s) \
226 ({ \
227 unsigned long __limit = TASK_SIZE - 1; \
228 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \
229 register const void __user *__p asm("r0") = __ptr; \
230 register unsigned long __l asm("r1") = __limit; \
231 register int __e asm("r0"); \
232 __asm__ __volatile__ ( \
233 __asmeq("%0", "r0") __asmeq("%2", "r2") \
234 __asmeq("%3", "r1") \
235 "bl __put_user_" #__s \
236 : "=&r" (__e) \
237 : "0" (__p), "r" (__r2), "r" (__l) \
238 : "ip", "lr", "cc"); \
239 __err = __e; \
240 })
241
242 #else /* CONFIG_MMU */
243
244 #define __addr_ok(addr) ((void)(addr), 1)
245 #define __range_ok(addr, size) ((void)(addr), 0)
246
247 #define get_user(x, p) __get_user(x, p)
248 #define __put_user_check __put_user_nocheck
249
250 #endif /* CONFIG_MMU */
251
252 #define access_ok(addr, size) (__range_ok(addr, size) == 0)
253
254 #ifdef CONFIG_CPU_SPECTRE
255 /*
256 * When mitigating Spectre variant 1, it is not worth fixing the non-
257 * verifying accessors, because we need to add verification of the
258 * address space there. Force these to use the standard get_user()
259 * version instead.
260 */
261 #define __get_user(x, ptr) get_user(x, ptr)
262 #else
263
264 /*
265 * The "__xxx" versions of the user access functions do not verify the
266 * address space - it must have been done previously with a separate
267 * "access_ok()" call.
268 *
269 * The "xxx_error" versions set the third argument to EFAULT if an
270 * error occurs, and leave it unchanged on success. Note that these
271 * versions are void (ie, don't return a value as such).
272 */
273 #define __get_user(x, ptr) \
274 ({ \
275 long __gu_err = 0; \
276 __get_user_err((x), (ptr), __gu_err, TUSER()); \
277 __gu_err; \
278 })
279
280 #define __get_user_err(x, ptr, err, __t) \
281 do { \
282 unsigned long __gu_addr = (unsigned long)(ptr); \
283 unsigned long __gu_val; \
284 unsigned int __ua_flags; \
285 __chk_user_ptr(ptr); \
286 might_fault(); \
287 __ua_flags = uaccess_save_and_enable(); \
288 switch (sizeof(*(ptr))) { \
289 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break; \
290 case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break; \
291 case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break; \
292 default: (__gu_val) = __get_user_bad(); \
293 } \
294 uaccess_restore(__ua_flags); \
295 (x) = (__typeof__(*(ptr)))__gu_val; \
296 } while (0)
297 #endif
298
299 #define __get_user_asm(x, addr, err, instr) \
300 __asm__ __volatile__( \
301 "1: " instr " %1, [%2], #0\n" \
302 "2:\n" \
303 " .pushsection .text.fixup,\"ax\"\n" \
304 " .align 2\n" \
305 "3: mov %0, %3\n" \
306 " mov %1, #0\n" \
307 " b 2b\n" \
308 " .popsection\n" \
309 " .pushsection __ex_table,\"a\"\n" \
310 " .align 3\n" \
311 " .long 1b, 3b\n" \
312 " .popsection" \
313 : "+r" (err), "=&r" (x) \
314 : "r" (addr), "i" (-EFAULT) \
315 : "cc")
316
317 #define __get_user_asm_byte(x, addr, err, __t) \
318 __get_user_asm(x, addr, err, "ldrb" __t)
319
320 #if __LINUX_ARM_ARCH__ >= 6
321
322 #define __get_user_asm_half(x, addr, err, __t) \
323 __get_user_asm(x, addr, err, "ldrh" __t)
324
325 #else
326
327 #ifndef __ARMEB__
328 #define __get_user_asm_half(x, __gu_addr, err, __t) \
329 ({ \
330 unsigned long __b1, __b2; \
331 __get_user_asm_byte(__b1, __gu_addr, err, __t); \
332 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \
333 (x) = __b1 | (__b2 << 8); \
334 })
335 #else
336 #define __get_user_asm_half(x, __gu_addr, err, __t) \
337 ({ \
338 unsigned long __b1, __b2; \
339 __get_user_asm_byte(__b1, __gu_addr, err, __t); \
340 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \
341 (x) = (__b1 << 8) | __b2; \
342 })
343 #endif
344
345 #endif /* __LINUX_ARM_ARCH__ >= 6 */
346
347 #define __get_user_asm_word(x, addr, err, __t) \
348 __get_user_asm(x, addr, err, "ldr" __t)
349
350 #define __put_user_switch(x, ptr, __err, __fn) \
351 do { \
352 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \
353 __typeof__(*(ptr)) __pu_val = (x); \
354 unsigned int __ua_flags; \
355 might_fault(); \
356 __ua_flags = uaccess_save_and_enable(); \
357 switch (sizeof(*(ptr))) { \
358 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \
359 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \
360 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \
361 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \
362 default: __err = __put_user_bad(); break; \
363 } \
364 uaccess_restore(__ua_flags); \
365 } while (0)
366
367 #define put_user(x, ptr) \
368 ({ \
369 int __pu_err = 0; \
370 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \
371 __pu_err; \
372 })
373
374 #ifdef CONFIG_CPU_SPECTRE
375 /*
376 * When mitigating Spectre variant 1.1, all accessors need to include
377 * verification of the address space.
378 */
379 #define __put_user(x, ptr) put_user(x, ptr)
380
381 #else
382 #define __put_user(x, ptr) \
383 ({ \
384 long __pu_err = 0; \
385 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \
386 __pu_err; \
387 })
388
389 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \
390 do { \
391 unsigned long __pu_addr = (unsigned long)__pu_ptr; \
392 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\
393 } while (0)
394
395 #define __put_user_nocheck_1 __put_user_asm_byte
396 #define __put_user_nocheck_2 __put_user_asm_half
397 #define __put_user_nocheck_4 __put_user_asm_word
398 #define __put_user_nocheck_8 __put_user_asm_dword
399
400 #endif /* !CONFIG_CPU_SPECTRE */
401
402 #define __put_user_asm(x, __pu_addr, err, instr) \
403 __asm__ __volatile__( \
404 "1: " instr " %1, [%2], #0\n" \
405 "2:\n" \
406 " .pushsection .text.fixup,\"ax\"\n" \
407 " .align 2\n" \
408 "3: mov %0, %3\n" \
409 " b 2b\n" \
410 " .popsection\n" \
411 " .pushsection __ex_table,\"a\"\n" \
412 " .align 3\n" \
413 " .long 1b, 3b\n" \
414 " .popsection" \
415 : "+r" (err) \
416 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \
417 : "cc")
418
419 #define __put_user_asm_byte(x, __pu_addr, err, __t) \
420 __put_user_asm(x, __pu_addr, err, "strb" __t)
421
422 #if __LINUX_ARM_ARCH__ >= 6
423
424 #define __put_user_asm_half(x, __pu_addr, err, __t) \
425 __put_user_asm(x, __pu_addr, err, "strh" __t)
426
427 #else
428
429 #ifndef __ARMEB__
430 #define __put_user_asm_half(x, __pu_addr, err, __t) \
431 ({ \
432 unsigned long __temp = (__force unsigned long)(x); \
433 __put_user_asm_byte(__temp, __pu_addr, err, __t); \
434 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\
435 })
436 #else
437 #define __put_user_asm_half(x, __pu_addr, err, __t) \
438 ({ \
439 unsigned long __temp = (__force unsigned long)(x); \
440 __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t); \
441 __put_user_asm_byte(__temp, __pu_addr + 1, err, __t); \
442 })
443 #endif
444
445 #endif /* __LINUX_ARM_ARCH__ >= 6 */
446
447 #define __put_user_asm_word(x, __pu_addr, err, __t) \
448 __put_user_asm(x, __pu_addr, err, "str" __t)
449
450 #ifndef __ARMEB__
451 #define __reg_oper0 "%R2"
452 #define __reg_oper1 "%Q2"
453 #else
454 #define __reg_oper0 "%Q2"
455 #define __reg_oper1 "%R2"
456 #endif
457
458 #define __put_user_asm_dword(x, __pu_addr, err, __t) \
459 __asm__ __volatile__( \
460 ARM( "1: str" __t " " __reg_oper1 ", [%1], #4\n" ) \
461 ARM( "2: str" __t " " __reg_oper0 ", [%1]\n" ) \
462 THUMB( "1: str" __t " " __reg_oper1 ", [%1]\n" ) \
463 THUMB( "2: str" __t " " __reg_oper0 ", [%1, #4]\n" ) \
464 "3:\n" \
465 " .pushsection .text.fixup,\"ax\"\n" \
466 " .align 2\n" \
467 "4: mov %0, %3\n" \
468 " b 3b\n" \
469 " .popsection\n" \
470 " .pushsection __ex_table,\"a\"\n" \
471 " .align 3\n" \
472 " .long 1b, 4b\n" \
473 " .long 2b, 4b\n" \
474 " .popsection" \
475 : "+r" (err), "+r" (__pu_addr) \
476 : "r" (x), "i" (-EFAULT) \
477 : "cc")
478
479 #define HAVE_GET_KERNEL_NOFAULT
480
481 #define __get_kernel_nofault(dst, src, type, err_label) \
482 do { \
483 const type *__pk_ptr = (src); \
484 unsigned long __src = (unsigned long)(__pk_ptr); \
485 type __val; \
486 int __err = 0; \
487 switch (sizeof(type)) { \
488 case 1: __get_user_asm_byte(__val, __src, __err, ""); break; \
489 case 2: __get_user_asm_half(__val, __src, __err, ""); break; \
490 case 4: __get_user_asm_word(__val, __src, __err, ""); break; \
491 case 8: { \
492 u32 *__v32 = (u32*)&__val; \
493 __get_user_asm_word(__v32[0], __src, __err, ""); \
494 if (__err) \
495 break; \
496 __get_user_asm_word(__v32[1], __src+4, __err, ""); \
497 break; \
498 } \
499 default: __err = __get_user_bad(); break; \
500 } \
501 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) \
502 put_unaligned(__val, (type *)(dst)); \
503 else \
504 *(type *)(dst) = __val; /* aligned by caller */ \
505 if (__err) \
506 goto err_label; \
507 } while (0)
508
509 #define __put_kernel_nofault(dst, src, type, err_label) \
510 do { \
511 const type *__pk_ptr = (dst); \
512 unsigned long __dst = (unsigned long)__pk_ptr; \
513 int __err = 0; \
514 type __val = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) \
515 ? get_unaligned((type *)(src)) \
516 : *(type *)(src); /* aligned by caller */ \
517 switch (sizeof(type)) { \
518 case 1: __put_user_asm_byte(__val, __dst, __err, ""); break; \
519 case 2: __put_user_asm_half(__val, __dst, __err, ""); break; \
520 case 4: __put_user_asm_word(__val, __dst, __err, ""); break; \
521 case 8: __put_user_asm_dword(__val, __dst, __err, ""); break; \
522 default: __err = __put_user_bad(); break; \
523 } \
524 if (__err) \
525 goto err_label; \
526 } while (0)
527
528 #ifdef CONFIG_MMU
529 extern unsigned long __must_check
530 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
531
532 static inline unsigned long __must_check
raw_copy_from_user(void * to,const void __user * from,unsigned long n)533 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
534 {
535 unsigned int __ua_flags;
536
537 __ua_flags = uaccess_save_and_enable();
538 n = arm_copy_from_user(to, from, n);
539 uaccess_restore(__ua_flags);
540 return n;
541 }
542
543 extern unsigned long __must_check
544 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
545 extern unsigned long __must_check
546 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
547
548 static inline unsigned long __must_check
raw_copy_to_user(void __user * to,const void * from,unsigned long n)549 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
550 {
551 #ifndef CONFIG_UACCESS_WITH_MEMCPY
552 unsigned int __ua_flags;
553 __ua_flags = uaccess_save_and_enable();
554 n = arm_copy_to_user(to, from, n);
555 uaccess_restore(__ua_flags);
556 return n;
557 #else
558 return arm_copy_to_user(to, from, n);
559 #endif
560 }
561
562 extern unsigned long __must_check
563 arm_clear_user(void __user *addr, unsigned long n);
564 extern unsigned long __must_check
565 __clear_user_std(void __user *addr, unsigned long n);
566
567 static inline unsigned long __must_check
__clear_user(void __user * addr,unsigned long n)568 __clear_user(void __user *addr, unsigned long n)
569 {
570 unsigned int __ua_flags = uaccess_save_and_enable();
571 n = arm_clear_user(addr, n);
572 uaccess_restore(__ua_flags);
573 return n;
574 }
575
576 #else
577 static inline unsigned long
raw_copy_from_user(void * to,const void __user * from,unsigned long n)578 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
579 {
580 memcpy(to, (const void __force *)from, n);
581 return 0;
582 }
583 static inline unsigned long
raw_copy_to_user(void __user * to,const void * from,unsigned long n)584 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
585 {
586 memcpy((void __force *)to, from, n);
587 return 0;
588 }
589 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0)
590 #endif
591 #define INLINE_COPY_TO_USER
592 #define INLINE_COPY_FROM_USER
593
clear_user(void __user * to,unsigned long n)594 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
595 {
596 if (access_ok(to, n))
597 n = __clear_user(to, n);
598 return n;
599 }
600
601 /* These are from lib/ code, and use __get_user() and friends */
602 extern long strncpy_from_user(char *dest, const char __user *src, long count);
603
604 extern __must_check long strnlen_user(const char __user *str, long n);
605
606 #endif /* _ASMARM_UACCESS_H */
607