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

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