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