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