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                 : "0" (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), "0" (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                 : "0" (__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                 : "0" (__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                 : "0" (__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         unsigned int __ua_flags = uaccess_save_and_enable();
 514         n = arm_copy_to_user(to, from, n);
 515         uaccess_restore(__ua_flags);
 516         return n;
 517 }
 518
 519 extern unsigned long __must_check
 520 arm_clear_user(void __user *addr, unsigned long n);
 521 extern unsigned long __must_check
 522 __clear_user_std(void __user *addr, unsigned long n);
 523
 524 static inline unsigned long __must_check
 525 __clear_user(void __user *addr, unsigned long n)
 526 {
 527         unsigned int __ua_flags = uaccess_save_and_enable();
 528         n = arm_clear_user(addr, n);
 529         uaccess_restore(__ua_flags);
 530         return n;
 531 }
 532
 533 #else
 534 #define __copy_from_user(to, from, n)   (memcpy(to, (void __force *)from, n), 0)
 535 #define __copy_to_user(to, from, n)     (memcpy((void __force *)to, from, n), 0)
 536 #define __clear_user(addr, n)           (memset((void __force *)addr, 0, n), 0)
 537 #endif
 538
 539 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 540 {
 541         if (access_ok(VERIFY_READ, from, n))
 542                 n = __copy_from_user(to, from, n);
 543         else /* security hole - plug it */
 544                 memset(to, 0, n);
 545         return n;
 546 }
 547
 548 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
 549 {
 550         if (access_ok(VERIFY_WRITE, to, n))
 551                 n = __copy_to_user(to, from, n);
 552         return n;
 553 }
 554
 555 #define __copy_to_user_inatomic __copy_to_user
 556 #define __copy_from_user_inatomic __copy_from_user
 557
 558 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 559 {
 560         if (access_ok(VERIFY_WRITE, to, n))
 561                 n = __clear_user(to, n);
 562         return n;
 563 }
 564
 565 /* These are from lib/ code, and use __get_user() and friends */
 566 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 567
 568 extern __must_check long strlen_user(const char __user *str);
 569 extern __must_check long strnlen_user(const char __user *str, long n);
 570
 571 #endif /* _ASMARM_UACCESS_H */