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