1 #ifndef _ASM_X86_UACCESS_H 2 #define _ASM_X86_UACCESS_H 3 /* 4 * User space memory access functions 5 */ 6 #include <linux/errno.h> 7 #include <linux/compiler.h> 8 #include <linux/thread_info.h> 9 #include <linux/string.h> 10 #include <asm/asm.h> 11 #include <asm/page.h> 12 #include <asm/smap.h> 13 14 #define VERIFY_READ 0 15 #define VERIFY_WRITE 1 16 17 /* 18 * The fs value determines whether argument validity checking should be 19 * performed or not. If get_fs() == USER_DS, checking is performed, with 20 * get_fs() == KERNEL_DS, checking is bypassed. 21 * 22 * For historical reasons, these macros are grossly misnamed. 23 */ 24 25 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) }) 26 27 #define KERNEL_DS MAKE_MM_SEG(-1UL) 28 #define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX) 29 30 #define get_ds() (KERNEL_DS) 31 #define get_fs() (current_thread_info()->addr_limit) 32 #define set_fs(x) (current_thread_info()->addr_limit = (x)) 33 34 #define segment_eq(a, b) ((a).seg == (b).seg) 35 36 #define user_addr_max() (current_thread_info()->addr_limit.seg) 37 #define __addr_ok(addr) \ 38 ((unsigned long __force)(addr) < user_addr_max()) 39 40 /* 41 * Test whether a block of memory is a valid user space address. 42 * Returns 0 if the range is valid, nonzero otherwise. 43 * 44 * This is equivalent to the following test: 45 * (u33)addr + (u33)size > (u33)current->addr_limit.seg (u65 for x86_64) 46 * 47 * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry... 48 */ 49 50 #define __range_not_ok(addr, size, limit) \ 51 ({ \ 52 unsigned long flag, roksum; \ 53 __chk_user_ptr(addr); \ 54 asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0" \ 55 : "=&r" (flag), "=r" (roksum) \ 56 : "1" (addr), "g" ((long)(size)), \ 57 "rm" (limit)); \ 58 flag; \ 59 }) 60 61 /** 62 * access_ok: - Checks if a user space pointer is valid 63 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that 64 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe 65 * to write to a block, it is always safe to read from it. 66 * @addr: User space pointer to start of block to check 67 * @size: Size of block to check 68 * 69 * Context: User context only. This function may sleep. 70 * 71 * Checks if a pointer to a block of memory in user space is valid. 72 * 73 * Returns true (nonzero) if the memory block may be valid, false (zero) 74 * if it is definitely invalid. 75 * 76 * Note that, depending on architecture, this function probably just 77 * checks that the pointer is in the user space range - after calling 78 * this function, memory access functions may still return -EFAULT. 79 */ 80 #define access_ok(type, addr, size) \ 81 (likely(__range_not_ok(addr, size, user_addr_max()) == 0)) 82 83 /* 84 * The exception table consists of pairs of addresses relative to the 85 * exception table enty itself: the first is the address of an 86 * instruction that is allowed to fault, and the second is the address 87 * at which the program should continue. No registers are modified, 88 * so it is entirely up to the continuation code to figure out what to 89 * do. 90 * 91 * All the routines below use bits of fixup code that are out of line 92 * with the main instruction path. This means when everything is well, 93 * we don't even have to jump over them. Further, they do not intrude 94 * on our cache or tlb entries. 95 */ 96 97 struct exception_table_entry { 98 int insn, fixup; 99 }; 100 /* This is not the generic standard exception_table_entry format */ 101 #define ARCH_HAS_SORT_EXTABLE 102 #define ARCH_HAS_SEARCH_EXTABLE 103 104 extern int fixup_exception(struct pt_regs *regs); 105 extern int early_fixup_exception(unsigned long *ip); 106 107 /* 108 * These are the main single-value transfer routines. They automatically 109 * use the right size if we just have the right pointer type. 110 * 111 * This gets kind of ugly. We want to return _two_ values in "get_user()" 112 * and yet we don't want to do any pointers, because that is too much 113 * of a performance impact. Thus we have a few rather ugly macros here, 114 * and hide all the ugliness from the user. 115 * 116 * The "__xxx" versions of the user access functions are versions that 117 * do not verify the address space, that must have been done previously 118 * with a separate "access_ok()" call (this is used when we do multiple 119 * accesses to the same area of user memory). 120 */ 121 122 extern int __get_user_1(void); 123 extern int __get_user_2(void); 124 extern int __get_user_4(void); 125 extern int __get_user_8(void); 126 extern int __get_user_bad(void); 127 128 /* 129 * This is a type: either unsigned long, if the argument fits into 130 * that type, or otherwise unsigned long long. 131 */ 132 #define __inttype(x) \ 133 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) 134 135 /** 136 * get_user: - Get a simple variable from user space. 137 * @x: Variable to store result. 138 * @ptr: Source address, in user space. 139 * 140 * Context: User context only. This function may sleep. 141 * 142 * This macro copies a single simple variable from user space to kernel 143 * space. It supports simple types like char and int, but not larger 144 * data types like structures or arrays. 145 * 146 * @ptr must have pointer-to-simple-variable type, and the result of 147 * dereferencing @ptr must be assignable to @x without a cast. 148 * 149 * Returns zero on success, or -EFAULT on error. 150 * On error, the variable @x is set to zero. 151 */ 152 /* 153 * Careful: we have to cast the result to the type of the pointer 154 * for sign reasons. 155 * 156 * The use of _ASM_DX as the register specifier is a bit of a 157 * simplification, as gcc only cares about it as the starting point 158 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits 159 * (%ecx being the next register in gcc's x86 register sequence), and 160 * %rdx on 64 bits. 161 * 162 * Clang/LLVM cares about the size of the register, but still wants 163 * the base register for something that ends up being a pair. 164 */ 165 #define get_user(x, ptr) \ 166 ({ \ 167 int __ret_gu; \ 168 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ 169 __chk_user_ptr(ptr); \ 170 might_fault(); \ 171 asm volatile("call __get_user_%P3" \ 172 : "=a" (__ret_gu), "=r" (__val_gu) \ 173 : "0" (ptr), "i" (sizeof(*(ptr)))); \ 174 (x) = (__typeof__(*(ptr))) __val_gu; \ 175 __ret_gu; \ 176 }) 177 178 #define __put_user_x(size, x, ptr, __ret_pu) \ 179 asm volatile("call __put_user_" #size : "=a" (__ret_pu) \ 180 : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx") 181 182 183 184 #ifdef CONFIG_X86_32 185 #define __put_user_asm_u64(x, addr, err, errret) \ 186 asm volatile(ASM_STAC "\n" \ 187 "1: movl %%eax,0(%2)\n" \ 188 "2: movl %%edx,4(%2)\n" \ 189 "3: " ASM_CLAC "\n" \ 190 ".section .fixup,\"ax\"\n" \ 191 "4: movl %3,%0\n" \ 192 " jmp 3b\n" \ 193 ".previous\n" \ 194 _ASM_EXTABLE(1b, 4b) \ 195 _ASM_EXTABLE(2b, 4b) \ 196 : "=r" (err) \ 197 : "A" (x), "r" (addr), "i" (errret), "0" (err)) 198 199 #define __put_user_asm_ex_u64(x, addr) \ 200 asm volatile(ASM_STAC "\n" \ 201 "1: movl %%eax,0(%1)\n" \ 202 "2: movl %%edx,4(%1)\n" \ 203 "3: " ASM_CLAC "\n" \ 204 _ASM_EXTABLE_EX(1b, 2b) \ 205 _ASM_EXTABLE_EX(2b, 3b) \ 206 : : "A" (x), "r" (addr)) 207 208 #define __put_user_x8(x, ptr, __ret_pu) \ 209 asm volatile("call __put_user_8" : "=a" (__ret_pu) \ 210 : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx") 211 #else 212 #define __put_user_asm_u64(x, ptr, retval, errret) \ 213 __put_user_asm(x, ptr, retval, "q", "", "er", errret) 214 #define __put_user_asm_ex_u64(x, addr) \ 215 __put_user_asm_ex(x, addr, "q", "", "er") 216 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu) 217 #endif 218 219 extern void __put_user_bad(void); 220 221 /* 222 * Strange magic calling convention: pointer in %ecx, 223 * value in %eax(:%edx), return value in %eax. clobbers %rbx 224 */ 225 extern void __put_user_1(void); 226 extern void __put_user_2(void); 227 extern void __put_user_4(void); 228 extern void __put_user_8(void); 229 230 /** 231 * put_user: - Write a simple value into user space. 232 * @x: Value to copy to user space. 233 * @ptr: Destination address, in user space. 234 * 235 * Context: User context only. This function may sleep. 236 * 237 * This macro copies a single simple value from kernel space to user 238 * space. It supports simple types like char and int, but not larger 239 * data types like structures or arrays. 240 * 241 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 242 * to the result of dereferencing @ptr. 243 * 244 * Returns zero on success, or -EFAULT on error. 245 */ 246 #define put_user(x, ptr) \ 247 ({ \ 248 int __ret_pu; \ 249 __typeof__(*(ptr)) __pu_val; \ 250 __chk_user_ptr(ptr); \ 251 might_fault(); \ 252 __pu_val = x; \ 253 switch (sizeof(*(ptr))) { \ 254 case 1: \ 255 __put_user_x(1, __pu_val, ptr, __ret_pu); \ 256 break; \ 257 case 2: \ 258 __put_user_x(2, __pu_val, ptr, __ret_pu); \ 259 break; \ 260 case 4: \ 261 __put_user_x(4, __pu_val, ptr, __ret_pu); \ 262 break; \ 263 case 8: \ 264 __put_user_x8(__pu_val, ptr, __ret_pu); \ 265 break; \ 266 default: \ 267 __put_user_x(X, __pu_val, ptr, __ret_pu); \ 268 break; \ 269 } \ 270 __ret_pu; \ 271 }) 272 273 #define __put_user_size(x, ptr, size, retval, errret) \ 274 do { \ 275 retval = 0; \ 276 __chk_user_ptr(ptr); \ 277 switch (size) { \ 278 case 1: \ 279 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \ 280 break; \ 281 case 2: \ 282 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \ 283 break; \ 284 case 4: \ 285 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \ 286 break; \ 287 case 8: \ 288 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval, \ 289 errret); \ 290 break; \ 291 default: \ 292 __put_user_bad(); \ 293 } \ 294 } while (0) 295 296 #define __put_user_size_ex(x, ptr, size) \ 297 do { \ 298 __chk_user_ptr(ptr); \ 299 switch (size) { \ 300 case 1: \ 301 __put_user_asm_ex(x, ptr, "b", "b", "iq"); \ 302 break; \ 303 case 2: \ 304 __put_user_asm_ex(x, ptr, "w", "w", "ir"); \ 305 break; \ 306 case 4: \ 307 __put_user_asm_ex(x, ptr, "l", "k", "ir"); \ 308 break; \ 309 case 8: \ 310 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr); \ 311 break; \ 312 default: \ 313 __put_user_bad(); \ 314 } \ 315 } while (0) 316 317 #ifdef CONFIG_X86_32 318 #define __get_user_asm_u64(x, ptr, retval, errret) (x) = __get_user_bad() 319 #define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad() 320 #else 321 #define __get_user_asm_u64(x, ptr, retval, errret) \ 322 __get_user_asm(x, ptr, retval, "q", "", "=r", errret) 323 #define __get_user_asm_ex_u64(x, ptr) \ 324 __get_user_asm_ex(x, ptr, "q", "", "=r") 325 #endif 326 327 #define __get_user_size(x, ptr, size, retval, errret) \ 328 do { \ 329 retval = 0; \ 330 __chk_user_ptr(ptr); \ 331 switch (size) { \ 332 case 1: \ 333 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \ 334 break; \ 335 case 2: \ 336 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \ 337 break; \ 338 case 4: \ 339 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \ 340 break; \ 341 case 8: \ 342 __get_user_asm_u64(x, ptr, retval, errret); \ 343 break; \ 344 default: \ 345 (x) = __get_user_bad(); \ 346 } \ 347 } while (0) 348 349 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \ 350 asm volatile(ASM_STAC "\n" \ 351 "1: mov"itype" %2,%"rtype"1\n" \ 352 "2: " ASM_CLAC "\n" \ 353 ".section .fixup,\"ax\"\n" \ 354 "3: mov %3,%0\n" \ 355 " xor"itype" %"rtype"1,%"rtype"1\n" \ 356 " jmp 2b\n" \ 357 ".previous\n" \ 358 _ASM_EXTABLE(1b, 3b) \ 359 : "=r" (err), ltype(x) \ 360 : "m" (__m(addr)), "i" (errret), "0" (err)) 361 362 #define __get_user_size_ex(x, ptr, size) \ 363 do { \ 364 __chk_user_ptr(ptr); \ 365 switch (size) { \ 366 case 1: \ 367 __get_user_asm_ex(x, ptr, "b", "b", "=q"); \ 368 break; \ 369 case 2: \ 370 __get_user_asm_ex(x, ptr, "w", "w", "=r"); \ 371 break; \ 372 case 4: \ 373 __get_user_asm_ex(x, ptr, "l", "k", "=r"); \ 374 break; \ 375 case 8: \ 376 __get_user_asm_ex_u64(x, ptr); \ 377 break; \ 378 default: \ 379 (x) = __get_user_bad(); \ 380 } \ 381 } while (0) 382 383 #define __get_user_asm_ex(x, addr, itype, rtype, ltype) \ 384 asm volatile("1: mov"itype" %1,%"rtype"0\n" \ 385 "2:\n" \ 386 _ASM_EXTABLE_EX(1b, 2b) \ 387 : ltype(x) : "m" (__m(addr))) 388 389 #define __put_user_nocheck(x, ptr, size) \ 390 ({ \ 391 int __pu_err; \ 392 __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \ 393 __pu_err; \ 394 }) 395 396 #define __get_user_nocheck(x, ptr, size) \ 397 ({ \ 398 int __gu_err; \ 399 unsigned long __gu_val; \ 400 __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \ 401 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 402 __gu_err; \ 403 }) 404 405 /* FIXME: this hack is definitely wrong -AK */ 406 struct __large_struct { unsigned long buf[100]; }; 407 #define __m(x) (*(struct __large_struct __user *)(x)) 408 409 /* 410 * Tell gcc we read from memory instead of writing: this is because 411 * we do not write to any memory gcc knows about, so there are no 412 * aliasing issues. 413 */ 414 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \ 415 asm volatile(ASM_STAC "\n" \ 416 "1: mov"itype" %"rtype"1,%2\n" \ 417 "2: " ASM_CLAC "\n" \ 418 ".section .fixup,\"ax\"\n" \ 419 "3: mov %3,%0\n" \ 420 " jmp 2b\n" \ 421 ".previous\n" \ 422 _ASM_EXTABLE(1b, 3b) \ 423 : "=r"(err) \ 424 : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err)) 425 426 #define __put_user_asm_ex(x, addr, itype, rtype, ltype) \ 427 asm volatile("1: mov"itype" %"rtype"0,%1\n" \ 428 "2:\n" \ 429 _ASM_EXTABLE_EX(1b, 2b) \ 430 : : ltype(x), "m" (__m(addr))) 431 432 /* 433 * uaccess_try and catch 434 */ 435 #define uaccess_try do { \ 436 current_thread_info()->uaccess_err = 0; \ 437 stac(); \ 438 barrier(); 439 440 #define uaccess_catch(err) \ 441 clac(); \ 442 (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0); \ 443 } while (0) 444 445 /** 446 * __get_user: - Get a simple variable from user space, with less checking. 447 * @x: Variable to store result. 448 * @ptr: Source address, in user space. 449 * 450 * Context: User context only. This function may sleep. 451 * 452 * This macro copies a single simple variable from user space to kernel 453 * space. It supports simple types like char and int, but not larger 454 * data types like structures or arrays. 455 * 456 * @ptr must have pointer-to-simple-variable type, and the result of 457 * dereferencing @ptr must be assignable to @x without a cast. 458 * 459 * Caller must check the pointer with access_ok() before calling this 460 * function. 461 * 462 * Returns zero on success, or -EFAULT on error. 463 * On error, the variable @x is set to zero. 464 */ 465 466 #define __get_user(x, ptr) \ 467 __get_user_nocheck((x), (ptr), sizeof(*(ptr))) 468 469 /** 470 * __put_user: - Write a simple value into user space, with less checking. 471 * @x: Value to copy to user space. 472 * @ptr: Destination address, in user space. 473 * 474 * Context: User context only. This function may sleep. 475 * 476 * This macro copies a single simple value from kernel space to user 477 * space. It supports simple types like char and int, but not larger 478 * data types like structures or arrays. 479 * 480 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 481 * to the result of dereferencing @ptr. 482 * 483 * Caller must check the pointer with access_ok() before calling this 484 * function. 485 * 486 * Returns zero on success, or -EFAULT on error. 487 */ 488 489 #define __put_user(x, ptr) \ 490 __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) 491 492 #define __get_user_unaligned __get_user 493 #define __put_user_unaligned __put_user 494 495 /* 496 * {get|put}_user_try and catch 497 * 498 * get_user_try { 499 * get_user_ex(...); 500 * } get_user_catch(err) 501 */ 502 #define get_user_try uaccess_try 503 #define get_user_catch(err) uaccess_catch(err) 504 505 #define get_user_ex(x, ptr) do { \ 506 unsigned long __gue_val; \ 507 __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr)))); \ 508 (x) = (__force __typeof__(*(ptr)))__gue_val; \ 509 } while (0) 510 511 #define put_user_try uaccess_try 512 #define put_user_catch(err) uaccess_catch(err) 513 514 #define put_user_ex(x, ptr) \ 515 __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) 516 517 extern unsigned long 518 copy_from_user_nmi(void *to, const void __user *from, unsigned long n); 519 extern __must_check long 520 strncpy_from_user(char *dst, const char __user *src, long count); 521 522 extern __must_check long strlen_user(const char __user *str); 523 extern __must_check long strnlen_user(const char __user *str, long n); 524 525 unsigned long __must_check clear_user(void __user *mem, unsigned long len); 526 unsigned long __must_check __clear_user(void __user *mem, unsigned long len); 527 528 /* 529 * movsl can be slow when source and dest are not both 8-byte aligned 530 */ 531 #ifdef CONFIG_X86_INTEL_USERCOPY 532 extern struct movsl_mask { 533 int mask; 534 } ____cacheline_aligned_in_smp movsl_mask; 535 #endif 536 537 #define ARCH_HAS_NOCACHE_UACCESS 1 538 539 #ifdef CONFIG_X86_32 540 # include <asm/uaccess_32.h> 541 #else 542 # include <asm/uaccess_64.h> 543 #endif 544 545 unsigned long __must_check _copy_from_user(void *to, const void __user *from, 546 unsigned n); 547 unsigned long __must_check _copy_to_user(void __user *to, const void *from, 548 unsigned n); 549 550 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS 551 # define copy_user_diag __compiletime_error 552 #else 553 # define copy_user_diag __compiletime_warning 554 #endif 555 556 extern void copy_user_diag("copy_from_user() buffer size is too small") 557 copy_from_user_overflow(void); 558 extern void copy_user_diag("copy_to_user() buffer size is too small") 559 copy_to_user_overflow(void) __asm__("copy_from_user_overflow"); 560 561 #undef copy_user_diag 562 563 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS 564 565 extern void 566 __compiletime_warning("copy_from_user() buffer size is not provably correct") 567 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow"); 568 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow() 569 570 extern void 571 __compiletime_warning("copy_to_user() buffer size is not provably correct") 572 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow"); 573 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow() 574 575 #else 576 577 static inline void 578 __copy_from_user_overflow(int size, unsigned long count) 579 { 580 WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count); 581 } 582 583 #define __copy_to_user_overflow __copy_from_user_overflow 584 585 #endif 586 587 static inline unsigned long __must_check 588 copy_from_user(void *to, const void __user *from, unsigned long n) 589 { 590 int sz = __compiletime_object_size(to); 591 592 might_fault(); 593 594 /* 595 * While we would like to have the compiler do the checking for us 596 * even in the non-constant size case, any false positives there are 597 * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even 598 * without - the [hopefully] dangerous looking nature of the warning 599 * would make people go look at the respecitive call sites over and 600 * over again just to find that there's no problem). 601 * 602 * And there are cases where it's just not realistic for the compiler 603 * to prove the count to be in range. For example when multiple call 604 * sites of a helper function - perhaps in different source files - 605 * all doing proper range checking, yet the helper function not doing 606 * so again. 607 * 608 * Therefore limit the compile time checking to the constant size 609 * case, and do only runtime checking for non-constant sizes. 610 */ 611 612 if (likely(sz < 0 || sz >= n)) 613 n = _copy_from_user(to, from, n); 614 else if(__builtin_constant_p(n)) 615 copy_from_user_overflow(); 616 else 617 __copy_from_user_overflow(sz, n); 618 619 return n; 620 } 621 622 static inline unsigned long __must_check 623 copy_to_user(void __user *to, const void *from, unsigned long n) 624 { 625 int sz = __compiletime_object_size(from); 626 627 might_fault(); 628 629 /* See the comment in copy_from_user() above. */ 630 if (likely(sz < 0 || sz >= n)) 631 n = _copy_to_user(to, from, n); 632 else if(__builtin_constant_p(n)) 633 copy_to_user_overflow(); 634 else 635 __copy_to_user_overflow(sz, n); 636 637 return n; 638 } 639 640 #undef __copy_from_user_overflow 641 #undef __copy_to_user_overflow 642 643 #endif /* _ASM_X86_UACCESS_H */ 644 645