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 #ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
  21 #include <asm-generic/uaccess-unaligned.h>
  22 #else
  23 #define __get_user_unaligned __get_user
  24 #define __put_user_unaligned __put_user
  25 #endif
  26
  27 #include <asm/extable.h>
  28
  29 /*
  30  * These two functions allow hooking accesses to userspace to increase
  31  * system integrity by ensuring that the kernel can not inadvertantly
  32  * perform such accesses (eg, via list poison values) which could then
  33  * be exploited for priviledge escalation.
  34  */
  35 static inline unsigned int uaccess_save_and_enable(void)
  36 {
  37 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  38         unsigned int old_domain = get_domain();
  39
  40         /* Set the current domain access to permit user accesses */
  41         set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
  42                    domain_val(DOMAIN_USER, DOMAIN_CLIENT));
  43
  44         return old_domain;
  45 #else
  46         return 0;
  47 #endif
  48 }
  49
  50 static inline void uaccess_restore(unsigned int flags)
  51 {
  52 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  53         /* Restore the user access mask */
  54         set_domain(flags);
  55 #endif
  56 }
  57
  58 /*
  59  * These two are intentionally not defined anywhere - if the kernel
  60  * code generates any references to them, that's a bug.
  61  */
  62 extern int __get_user_bad(void);
  63 extern int __put_user_bad(void);
  64
  65 /*
  66  * Note that this is actually 0x1,0000,0000
  67  */
  68 #define KERNEL_DS       0x00000000
  69 #define get_ds()        (KERNEL_DS)
  70
  71 #ifdef CONFIG_MMU
  72
  73 #define USER_DS         TASK_SIZE
  74 #define get_fs()        (current_thread_info()->addr_limit)
  75
  76 static inline void set_fs(mm_segment_t fs)
  77 {
  78         current_thread_info()->addr_limit = fs;
  79         modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
  80 }
  81
  82 #define segment_eq(a, b)        ((a) == (b))
  83
  84 /* We use 33-bit arithmetic here... */
  85 #define __range_ok(addr, size) ({ \
  86         unsigned long flag, roksum; \
  87         __chk_user_ptr(addr);   \
  88         __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
  89                 : "=&r" (flag), "=&r" (roksum) \
  90                 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
  91                 : "cc"); \
  92         flag; })
  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 const typeof(*(p)) __user *__p asm("r0") = (p);\
 163                 register typeof(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 /*
 254  * The "__xxx" versions of the user access functions do not verify the
 255  * address space - it must have been done previously with a separate
 256  * "access_ok()" call.
 257  *
 258  * The "xxx_error" versions set the third argument to EFAULT if an
 259  * error occurs, and leave it unchanged on success.  Note that these
 260  * versions are void (ie, don't return a value as such).
 261  */
 262 #define __get_user(x, ptr)                                              \
 263 ({                                                                      \
 264         long __gu_err = 0;                                              \
 265         __get_user_err((x), (ptr), __gu_err);                           \
 266         __gu_err;                                                       \
 267 })
 268
 269 #define __get_user_error(x, ptr, err)                                   \
 270 ({                                                                      \
 271         __get_user_err((x), (ptr), err);                                \
 272         (void) 0;                                                       \
 273 })
 274
 275 #define __get_user_err(x, ptr, err)                                     \
 276 do {                                                                    \
 277         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 278         unsigned long __gu_val;                                         \
 279         unsigned int __ua_flags;                                        \
 280         __chk_user_ptr(ptr);                                            \
 281         might_fault();                                                  \
 282         __ua_flags = uaccess_save_and_enable();                         \
 283         switch (sizeof(*(ptr))) {                                       \
 284         case 1: __get_user_asm_byte(__gu_val, __gu_addr, err);  break;  \
 285         case 2: __get_user_asm_half(__gu_val, __gu_addr, err);  break;  \
 286         case 4: __get_user_asm_word(__gu_val, __gu_addr, err);  break;  \
 287         default: (__gu_val) = __get_user_bad();                         \
 288         }                                                               \
 289         uaccess_restore(__ua_flags);                                    \
 290         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 291 } while (0)
 292
 293 #define __get_user_asm(x, addr, err, instr)                     \
 294         __asm__ __volatile__(                                   \
 295         "1:     " TUSER(instr) " %1, [%2], #0\n"                \
 296         "2:\n"                                                  \
 297         "       .pushsection .text.fixup,\"ax\"\n"              \
 298         "       .align  2\n"                                    \
 299         "3:     mov     %0, %3\n"                               \
 300         "       mov     %1, #0\n"                               \
 301         "       b       2b\n"                                   \
 302         "       .popsection\n"                                  \
 303         "       .pushsection __ex_table,\"a\"\n"                \
 304         "       .align  3\n"                                    \
 305         "       .long   1b, 3b\n"                               \
 306         "       .popsection"                                    \
 307         : "+r" (err), "=&r" (x)                                 \
 308         : "r" (addr), "i" (-EFAULT)                             \
 309         : "cc")
 310
 311 #define __get_user_asm_byte(x, addr, err)                       \
 312         __get_user_asm(x, addr, err, ldrb)
 313
 314 #ifndef __ARMEB__
 315 #define __get_user_asm_half(x, __gu_addr, err)                  \
 316 ({                                                              \
 317         unsigned long __b1, __b2;                               \
 318         __get_user_asm_byte(__b1, __gu_addr, err);              \
 319         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 320         (x) = __b1 | (__b2 << 8);                               \
 321 })
 322 #else
 323 #define __get_user_asm_half(x, __gu_addr, err)                  \
 324 ({                                                              \
 325         unsigned long __b1, __b2;                               \
 326         __get_user_asm_byte(__b1, __gu_addr, err);              \
 327         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 328         (x) = (__b1 << 8) | __b2;                               \
 329 })
 330 #endif
 331
 332 #define __get_user_asm_word(x, addr, err)                       \
 333         __get_user_asm(x, addr, err, ldr)
 334
 335
 336 #define __put_user_switch(x, ptr, __err, __fn)                          \
 337         do {                                                            \
 338                 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr);      \
 339                 __typeof__(*(ptr)) __pu_val = (x);                      \
 340                 unsigned int __ua_flags;                                \
 341                 might_fault();                                          \
 342                 __ua_flags = uaccess_save_and_enable();                 \
 343                 switch (sizeof(*(ptr))) {                               \
 344                 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break;      \
 345                 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break;      \
 346                 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break;      \
 347                 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break;      \
 348                 default: __err = __put_user_bad(); break;               \
 349                 }                                                       \
 350                 uaccess_restore(__ua_flags);                            \
 351         } while (0)
 352
 353 #define put_user(x, ptr)                                                \
 354 ({                                                                      \
 355         int __pu_err = 0;                                               \
 356         __put_user_switch((x), (ptr), __pu_err, __put_user_check);      \
 357         __pu_err;                                                       \
 358 })
 359
 360 #define __put_user(x, ptr)                                              \
 361 ({                                                                      \
 362         long __pu_err = 0;                                              \
 363         __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck);    \
 364         __pu_err;                                                       \
 365 })
 366
 367 #define __put_user_error(x, ptr, err)                                   \
 368 ({                                                                      \
 369         __put_user_switch((x), (ptr), (err), __put_user_nocheck);       \
 370         (void) 0;                                                       \
 371 })
 372
 373 #define __put_user_nocheck(x, __pu_ptr, __err, __size)                  \
 374         do {                                                            \
 375                 unsigned long __pu_addr = (unsigned long)__pu_ptr;      \
 376                 __put_user_nocheck_##__size(x, __pu_addr, __err);       \
 377         } while (0)
 378
 379 #define __put_user_nocheck_1 __put_user_asm_byte
 380 #define __put_user_nocheck_2 __put_user_asm_half
 381 #define __put_user_nocheck_4 __put_user_asm_word
 382 #define __put_user_nocheck_8 __put_user_asm_dword
 383
 384 #define __put_user_asm(x, __pu_addr, err, instr)                \
 385         __asm__ __volatile__(                                   \
 386         "1:     " TUSER(instr) " %1, [%2], #0\n"                \
 387         "2:\n"                                                  \
 388         "       .pushsection .text.fixup,\"ax\"\n"              \
 389         "       .align  2\n"                                    \
 390         "3:     mov     %0, %3\n"                               \
 391         "       b       2b\n"                                   \
 392         "       .popsection\n"                                  \
 393         "       .pushsection __ex_table,\"a\"\n"                \
 394         "       .align  3\n"                                    \
 395         "       .long   1b, 3b\n"                               \
 396         "       .popsection"                                    \
 397         : "+r" (err)                                            \
 398         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 399         : "cc")
 400
 401 #define __put_user_asm_byte(x, __pu_addr, err)                  \
 402         __put_user_asm(x, __pu_addr, err, strb)
 403
 404 #ifndef __ARMEB__
 405 #define __put_user_asm_half(x, __pu_addr, err)                  \
 406 ({                                                              \
 407         unsigned long __temp = (__force unsigned long)(x);      \
 408         __put_user_asm_byte(__temp, __pu_addr, err);            \
 409         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 410 })
 411 #else
 412 #define __put_user_asm_half(x, __pu_addr, err)                  \
 413 ({                                                              \
 414         unsigned long __temp = (__force unsigned long)(x);      \
 415         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 416         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 417 })
 418 #endif
 419
 420 #define __put_user_asm_word(x, __pu_addr, err)                  \
 421         __put_user_asm(x, __pu_addr, err, str)
 422
 423 #ifndef __ARMEB__
 424 #define __reg_oper0     "%R2"
 425 #define __reg_oper1     "%Q2"
 426 #else
 427 #define __reg_oper0     "%Q2"
 428 #define __reg_oper1     "%R2"
 429 #endif
 430
 431 #define __put_user_asm_dword(x, __pu_addr, err)                 \
 432         __asm__ __volatile__(                                   \
 433  ARM(   "1:     " TUSER(str) "  " __reg_oper1 ", [%1], #4\n"    ) \
 434  ARM(   "2:     " TUSER(str) "  " __reg_oper0 ", [%1]\n"        ) \
 435  THUMB( "1:     " TUSER(str) "  " __reg_oper1 ", [%1]\n"        ) \
 436  THUMB( "2:     " TUSER(str) "  " __reg_oper0 ", [%1, #4]\n"    ) \
 437         "3:\n"                                                  \
 438         "       .pushsection .text.fixup,\"ax\"\n"              \
 439         "       .align  2\n"                                    \
 440         "4:     mov     %0, %3\n"                               \
 441         "       b       3b\n"                                   \
 442         "       .popsection\n"                                  \
 443         "       .pushsection __ex_table,\"a\"\n"                \
 444         "       .align  3\n"                                    \
 445         "       .long   1b, 4b\n"                               \
 446         "       .long   2b, 4b\n"                               \
 447         "       .popsection"                                    \
 448         : "+r" (err), "+r" (__pu_addr)                          \
 449         : "r" (x), "i" (-EFAULT)                                \
 450         : "cc")
 451
 452
 453 #ifdef CONFIG_MMU
 454 extern unsigned long __must_check
 455 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
 456
 457 static inline unsigned long __must_check
 458 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 459 {
 460         unsigned int __ua_flags;
 461
 462         __ua_flags = uaccess_save_and_enable();
 463         n = arm_copy_from_user(to, from, n);
 464         uaccess_restore(__ua_flags);
 465         return n;
 466 }
 467
 468 extern unsigned long __must_check
 469 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
 470 extern unsigned long __must_check
 471 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 472
 473 static inline unsigned long __must_check
 474 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 475 {
 476 #ifndef CONFIG_UACCESS_WITH_MEMCPY
 477         unsigned int __ua_flags;
 478         __ua_flags = uaccess_save_and_enable();
 479         n = arm_copy_to_user(to, from, n);
 480         uaccess_restore(__ua_flags);
 481         return n;
 482 #else
 483         return arm_copy_to_user(to, from, n);
 484 #endif
 485 }
 486
 487 extern unsigned long __must_check
 488 arm_clear_user(void __user *addr, unsigned long n);
 489 extern unsigned long __must_check
 490 __clear_user_std(void __user *addr, unsigned long n);
 491
 492 static inline unsigned long __must_check
 493 __clear_user(void __user *addr, unsigned long n)
 494 {
 495         unsigned int __ua_flags = uaccess_save_and_enable();
 496         n = arm_clear_user(addr, n);
 497         uaccess_restore(__ua_flags);
 498         return n;
 499 }
 500
 501 #else
 502 static inline unsigned long
 503 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 504 {
 505         memcpy(to, (const void __force *)from, n);
 506         return 0;
 507 }
 508 static inline unsigned long
 509 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 510 {
 511         memcpy((void __force *)to, from, n);
 512         return 0;
 513 }
 514 #define __clear_user(addr, n)           (memset((void __force *)addr, 0, n), 0)
 515 #endif
 516 #define INLINE_COPY_TO_USER
 517 #define INLINE_COPY_FROM_USER
 518
 519 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 520 {
 521         if (access_ok(VERIFY_WRITE, to, n))
 522                 n = __clear_user(to, n);
 523         return n;
 524 }
 525
 526 /* These are from lib/ code, and use __get_user() and friends */
 527 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 528
 529 extern __must_check long strlen_user(const char __user *str);
 530 extern __must_check long strnlen_user(const char __user *str, long n);
 531
 532 #endif /* _ASMARM_UACCESS_H */