Merge tag 'for-4.21' of git://git.armlinux.org.uk/~rmk/linux-arm
[sfrench/cifs-2.6.git] / arch / arm / include / asm / uaccess.h
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 #define get_ds()        (KERNEL_DS)
63
64 #ifdef CONFIG_MMU
65
66 #define USER_DS         TASK_SIZE
67 #define get_fs()        (current_thread_info()->addr_limit)
68
69 static inline void set_fs(mm_segment_t fs)
70 {
71         current_thread_info()->addr_limit = fs;
72
73         /*
74          * Prevent a mispredicted conditional call to set_fs from forwarding
75          * the wrong address limit to access_ok under speculation.
76          */
77         dsb(nsh);
78         isb();
79
80         modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
81 }
82
83 #define segment_eq(a, b)        ((a) == (b))
84
85 /* We use 33-bit arithmetic here... */
86 #define __range_ok(addr, size) ({ \
87         unsigned long flag, roksum; \
88         __chk_user_ptr(addr);   \
89         __asm__("adds %1, %2, %3; sbcccs %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 */