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  * This is a type: either unsigned long, if the argument fits into
  89  * that type, or otherwise unsigned long long.
  90  */
  91 #define __inttype(x) \
  92         __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
  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 typeof(*(p)) __user *__p asm("r0") = (p);      \
 163                 register __inttype(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 #ifdef CONFIG_CPU_SPECTRE
 254 /*
 255  * When mitigating Spectre variant 1, it is not worth fixing the non-
 256  * verifying accessors, because we need to add verification of the
 257  * address space there.  Force these to use the standard get_user()
 258  * version instead.
 259  */
 260 #define __get_user(x, ptr) get_user(x, ptr)
 261 #else
 262
 263 /*
 264  * The "__xxx" versions of the user access functions do not verify the
 265  * address space - it must have been done previously with a separate
 266  * "access_ok()" call.
 267  *
 268  * The "xxx_error" versions set the third argument to EFAULT if an
 269  * error occurs, and leave it unchanged on success.  Note that these
 270  * versions are void (ie, don't return a value as such).
 271  */
 272 #define __get_user(x, ptr)                                              \
 273 ({                                                                      \
 274         long __gu_err = 0;                                              \
 275         __get_user_err((x), (ptr), __gu_err);                           \
 276         __gu_err;                                                       \
 277 })
 278
 279 #define __get_user_err(x, ptr, err)                                     \
 280 do {                                                                    \
 281         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 282         unsigned long __gu_val;                                         \
 283         unsigned int __ua_flags;                                        \
 284         __chk_user_ptr(ptr);                                            \
 285         might_fault();                                                  \
 286         __ua_flags = uaccess_save_and_enable();                         \
 287         switch (sizeof(*(ptr))) {                                       \
 288         case 1: __get_user_asm_byte(__gu_val, __gu_addr, err);  break;  \
 289         case 2: __get_user_asm_half(__gu_val, __gu_addr, err);  break;  \
 290         case 4: __get_user_asm_word(__gu_val, __gu_addr, err);  break;  \
 291         default: (__gu_val) = __get_user_bad();                         \
 292         }                                                               \
 293         uaccess_restore(__ua_flags);                                    \
 294         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 295 } while (0)
 296
 297 #define __get_user_asm(x, addr, err, instr)                     \
 298         __asm__ __volatile__(                                   \
 299         "1:     " TUSER(instr) " %1, [%2], #0\n"                \
 300         "2:\n"                                                  \
 301         "       .pushsection .text.fixup,\"ax\"\n"              \
 302         "       .align  2\n"                                    \
 303         "3:     mov     %0, %3\n"                               \
 304         "       mov     %1, #0\n"                               \
 305         "       b       2b\n"                                   \
 306         "       .popsection\n"                                  \
 307         "       .pushsection __ex_table,\"a\"\n"                \
 308         "       .align  3\n"                                    \
 309         "       .long   1b, 3b\n"                               \
 310         "       .popsection"                                    \
 311         : "+r" (err), "=&r" (x)                                 \
 312         : "r" (addr), "i" (-EFAULT)                             \
 313         : "cc")
 314
 315 #define __get_user_asm_byte(x, addr, err)                       \
 316         __get_user_asm(x, addr, err, ldrb)
 317
 318 #ifndef __ARMEB__
 319 #define __get_user_asm_half(x, __gu_addr, err)                  \
 320 ({                                                              \
 321         unsigned long __b1, __b2;                               \
 322         __get_user_asm_byte(__b1, __gu_addr, err);              \
 323         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 324         (x) = __b1 | (__b2 << 8);                               \
 325 })
 326 #else
 327 #define __get_user_asm_half(x, __gu_addr, err)                  \
 328 ({                                                              \
 329         unsigned long __b1, __b2;                               \
 330         __get_user_asm_byte(__b1, __gu_addr, err);              \
 331         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 332         (x) = (__b1 << 8) | __b2;                               \
 333 })
 334 #endif
 335
 336 #define __get_user_asm_word(x, addr, err)                       \
 337         __get_user_asm(x, addr, err, ldr)
 338 #endif
 339
 340
 341 #define __put_user_switch(x, ptr, __err, __fn)                          \
 342         do {                                                            \
 343                 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr);      \
 344                 __typeof__(*(ptr)) __pu_val = (x);                      \
 345                 unsigned int __ua_flags;                                \
 346                 might_fault();                                          \
 347                 __ua_flags = uaccess_save_and_enable();                 \
 348                 switch (sizeof(*(ptr))) {                               \
 349                 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break;      \
 350                 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break;      \
 351                 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break;      \
 352                 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break;      \
 353                 default: __err = __put_user_bad(); break;               \
 354                 }                                                       \
 355                 uaccess_restore(__ua_flags);                            \
 356         } while (0)
 357
 358 #define put_user(x, ptr)                                                \
 359 ({                                                                      \
 360         int __pu_err = 0;                                               \
 361         __put_user_switch((x), (ptr), __pu_err, __put_user_check);      \
 362         __pu_err;                                                       \
 363 })
 364
 365 #define __put_user(x, ptr)                                              \
 366 ({                                                                      \
 367         long __pu_err = 0;                                              \
 368         __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck);    \
 369         __pu_err;                                                       \
 370 })
 371
 372 #define __put_user_error(x, ptr, err)                                   \
 373 ({                                                                      \
 374         __put_user_switch((x), (ptr), (err), __put_user_nocheck);       \
 375         (void) 0;                                                       \
 376 })
 377
 378 #define __put_user_nocheck(x, __pu_ptr, __err, __size)                  \
 379         do {                                                            \
 380                 unsigned long __pu_addr = (unsigned long)__pu_ptr;      \
 381                 __put_user_nocheck_##__size(x, __pu_addr, __err);       \
 382         } while (0)
 383
 384 #define __put_user_nocheck_1 __put_user_asm_byte
 385 #define __put_user_nocheck_2 __put_user_asm_half
 386 #define __put_user_nocheck_4 __put_user_asm_word
 387 #define __put_user_nocheck_8 __put_user_asm_dword
 388
 389 #define __put_user_asm(x, __pu_addr, err, instr)                \
 390         __asm__ __volatile__(                                   \
 391         "1:     " TUSER(instr) " %1, [%2], #0\n"                \
 392         "2:\n"                                                  \
 393         "       .pushsection .text.fixup,\"ax\"\n"              \
 394         "       .align  2\n"                                    \
 395         "3:     mov     %0, %3\n"                               \
 396         "       b       2b\n"                                   \
 397         "       .popsection\n"                                  \
 398         "       .pushsection __ex_table,\"a\"\n"                \
 399         "       .align  3\n"                                    \
 400         "       .long   1b, 3b\n"                               \
 401         "       .popsection"                                    \
 402         : "+r" (err)                                            \
 403         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 404         : "cc")
 405
 406 #define __put_user_asm_byte(x, __pu_addr, err)                  \
 407         __put_user_asm(x, __pu_addr, err, strb)
 408
 409 #ifndef __ARMEB__
 410 #define __put_user_asm_half(x, __pu_addr, err)                  \
 411 ({                                                              \
 412         unsigned long __temp = (__force unsigned long)(x);      \
 413         __put_user_asm_byte(__temp, __pu_addr, err);            \
 414         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 415 })
 416 #else
 417 #define __put_user_asm_half(x, __pu_addr, err)                  \
 418 ({                                                              \
 419         unsigned long __temp = (__force unsigned long)(x);      \
 420         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 421         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 422 })
 423 #endif
 424
 425 #define __put_user_asm_word(x, __pu_addr, err)                  \
 426         __put_user_asm(x, __pu_addr, err, str)
 427
 428 #ifndef __ARMEB__
 429 #define __reg_oper0     "%R2"
 430 #define __reg_oper1     "%Q2"
 431 #else
 432 #define __reg_oper0     "%Q2"
 433 #define __reg_oper1     "%R2"
 434 #endif
 435
 436 #define __put_user_asm_dword(x, __pu_addr, err)                 \
 437         __asm__ __volatile__(                                   \
 438  ARM(   "1:     " TUSER(str) "  " __reg_oper1 ", [%1], #4\n"    ) \
 439  ARM(   "2:     " TUSER(str) "  " __reg_oper0 ", [%1]\n"        ) \
 440  THUMB( "1:     " TUSER(str) "  " __reg_oper1 ", [%1]\n"        ) \
 441  THUMB( "2:     " TUSER(str) "  " __reg_oper0 ", [%1, #4]\n"    ) \
 442         "3:\n"                                                  \
 443         "       .pushsection .text.fixup,\"ax\"\n"              \
 444         "       .align  2\n"                                    \
 445         "4:     mov     %0, %3\n"                               \
 446         "       b       3b\n"                                   \
 447         "       .popsection\n"                                  \
 448         "       .pushsection __ex_table,\"a\"\n"                \
 449         "       .align  3\n"                                    \
 450         "       .long   1b, 4b\n"                               \
 451         "       .long   2b, 4b\n"                               \
 452         "       .popsection"                                    \
 453         : "+r" (err), "+r" (__pu_addr)                          \
 454         : "r" (x), "i" (-EFAULT)                                \
 455         : "cc")
 456
 457
 458 #ifdef CONFIG_MMU
 459 extern unsigned long __must_check
 460 arm_copy_from_user(void *to, const void __user *from, unsigned long n);
 461
 462 static inline unsigned long __must_check
 463 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 464 {
 465         unsigned int __ua_flags;
 466
 467         __ua_flags = uaccess_save_and_enable();
 468         n = arm_copy_from_user(to, from, n);
 469         uaccess_restore(__ua_flags);
 470         return n;
 471 }
 472
 473 extern unsigned long __must_check
 474 arm_copy_to_user(void __user *to, const void *from, unsigned long n);
 475 extern unsigned long __must_check
 476 __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 477
 478 static inline unsigned long __must_check
 479 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 480 {
 481 #ifndef CONFIG_UACCESS_WITH_MEMCPY
 482         unsigned int __ua_flags;
 483         __ua_flags = uaccess_save_and_enable();
 484         n = arm_copy_to_user(to, from, n);
 485         uaccess_restore(__ua_flags);
 486         return n;
 487 #else
 488         return arm_copy_to_user(to, from, n);
 489 #endif
 490 }
 491
 492 extern unsigned long __must_check
 493 arm_clear_user(void __user *addr, unsigned long n);
 494 extern unsigned long __must_check
 495 __clear_user_std(void __user *addr, unsigned long n);
 496
 497 static inline unsigned long __must_check
 498 __clear_user(void __user *addr, unsigned long n)
 499 {
 500         unsigned int __ua_flags = uaccess_save_and_enable();
 501         n = arm_clear_user(addr, n);
 502         uaccess_restore(__ua_flags);
 503         return n;
 504 }
 505
 506 #else
 507 static inline unsigned long
 508 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 509 {
 510         memcpy(to, (const void __force *)from, n);
 511         return 0;
 512 }
 513 static inline unsigned long
 514 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 515 {
 516         memcpy((void __force *)to, from, n);
 517         return 0;
 518 }
 519 #define __clear_user(addr, n)           (memset((void __force *)addr, 0, n), 0)
 520 #endif
 521 #define INLINE_COPY_TO_USER
 522 #define INLINE_COPY_FROM_USER
 523
 524 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 525 {
 526         if (access_ok(VERIFY_WRITE, to, n))
 527                 n = __clear_user(to, n);
 528         return n;
 529 }
 530
 531 /* These are from lib/ code, and use __get_user() and friends */
 532 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 533
 534 extern __must_check long strnlen_user(const char __user *str, long n);
 535
 536 #endif /* _ASMARM_UACCESS_H */