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/kasan-checks.h> 9 #include <linux/thread_info.h> 10 #include <linux/string.h> 11 #include <asm/asm.h> 12 #include <asm/page.h> 13 #include <asm/smap.h> 14 15 #define VERIFY_READ 0 16 #define VERIFY_WRITE 1 17 18 /* 19 * The fs value determines whether argument validity checking should be 20 * performed or not. If get_fs() == USER_DS, checking is performed, with 21 * get_fs() == KERNEL_DS, checking is bypassed. 22 * 23 * For historical reasons, these macros are grossly misnamed. 24 */ 25 26 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) }) 27 28 #define KERNEL_DS MAKE_MM_SEG(-1UL) 29 #define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX) 30 31 #define get_ds() (KERNEL_DS) 32 #define get_fs() (current_thread_info()->addr_limit) 33 #define set_fs(x) (current_thread_info()->addr_limit = (x)) 34 35 #define segment_eq(a, b) ((a).seg == (b).seg) 36 37 #define user_addr_max() (current_thread_info()->addr_limit.seg) 38 #define __addr_ok(addr) \ 39 ((unsigned long __force)(addr) < user_addr_max()) 40 41 /* 42 * Test whether a block of memory is a valid user space address. 43 * Returns 0 if the range is valid, nonzero otherwise. 44 */ 45 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit) 46 { 47 /* 48 * If we have used "sizeof()" for the size, 49 * we know it won't overflow the limit (but 50 * it might overflow the 'addr', so it's 51 * important to subtract the size from the 52 * limit, not add it to the address). 53 */ 54 if (__builtin_constant_p(size)) 55 return unlikely(addr > limit - size); 56 57 /* Arbitrary sizes? Be careful about overflow */ 58 addr += size; 59 if (unlikely(addr < size)) 60 return true; 61 return unlikely(addr > limit); 62 } 63 64 #define __range_not_ok(addr, size, limit) \ 65 ({ \ 66 __chk_user_ptr(addr); \ 67 __chk_range_not_ok((unsigned long __force)(addr), size, limit); \ 68 }) 69 70 /** 71 * access_ok: - Checks if a user space pointer is valid 72 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that 73 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe 74 * to write to a block, it is always safe to read from it. 75 * @addr: User space pointer to start of block to check 76 * @size: Size of block to check 77 * 78 * Context: User context only. This function may sleep if pagefaults are 79 * enabled. 80 * 81 * Checks if a pointer to a block of memory in user space is valid. 82 * 83 * Returns true (nonzero) if the memory block may be valid, false (zero) 84 * if it is definitely invalid. 85 * 86 * Note that, depending on architecture, this function probably just 87 * checks that the pointer is in the user space range - after calling 88 * this function, memory access functions may still return -EFAULT. 89 */ 90 #define access_ok(type, addr, size) \ 91 likely(!__range_not_ok(addr, size, user_addr_max())) 92 93 /* 94 * The exception table consists of triples of addresses relative to the 95 * exception table entry itself. The first address is of an instruction 96 * that is allowed to fault, the second is the target at which the program 97 * should continue. The third is a handler function to deal with the fault 98 * caused by the instruction in the first field. 99 * 100 * All the routines below use bits of fixup code that are out of line 101 * with the main instruction path. This means when everything is well, 102 * we don't even have to jump over them. Further, they do not intrude 103 * on our cache or tlb entries. 104 */ 105 106 struct exception_table_entry { 107 int insn, fixup, handler; 108 }; 109 110 #define ARCH_HAS_RELATIVE_EXTABLE 111 112 #define swap_ex_entry_fixup(a, b, tmp, delta) \ 113 do { \ 114 (a)->fixup = (b)->fixup + (delta); \ 115 (b)->fixup = (tmp).fixup - (delta); \ 116 (a)->handler = (b)->handler + (delta); \ 117 (b)->handler = (tmp).handler - (delta); \ 118 } while (0) 119 120 extern int fixup_exception(struct pt_regs *regs, int trapnr); 121 extern bool ex_has_fault_handler(unsigned long ip); 122 extern void early_fixup_exception(struct pt_regs *regs, int trapnr); 123 124 /* 125 * These are the main single-value transfer routines. They automatically 126 * use the right size if we just have the right pointer type. 127 * 128 * This gets kind of ugly. We want to return _two_ values in "get_user()" 129 * and yet we don't want to do any pointers, because that is too much 130 * of a performance impact. Thus we have a few rather ugly macros here, 131 * and hide all the ugliness from the user. 132 * 133 * The "__xxx" versions of the user access functions are versions that 134 * do not verify the address space, that must have been done previously 135 * with a separate "access_ok()" call (this is used when we do multiple 136 * accesses to the same area of user memory). 137 */ 138 139 extern int __get_user_1(void); 140 extern int __get_user_2(void); 141 extern int __get_user_4(void); 142 extern int __get_user_8(void); 143 extern int __get_user_bad(void); 144 145 #define __uaccess_begin() stac() 146 #define __uaccess_end() clac() 147 148 /* 149 * This is a type: either unsigned long, if the argument fits into 150 * that type, or otherwise unsigned long long. 151 */ 152 #define __inttype(x) \ 153 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) 154 155 /** 156 * get_user: - Get a simple variable from user space. 157 * @x: Variable to store result. 158 * @ptr: Source address, in user space. 159 * 160 * Context: User context only. This function may sleep if pagefaults are 161 * enabled. 162 * 163 * This macro copies a single simple variable from user space to kernel 164 * space. It supports simple types like char and int, but not larger 165 * data types like structures or arrays. 166 * 167 * @ptr must have pointer-to-simple-variable type, and the result of 168 * dereferencing @ptr must be assignable to @x without a cast. 169 * 170 * Returns zero on success, or -EFAULT on error. 171 * On error, the variable @x is set to zero. 172 */ 173 /* 174 * Careful: we have to cast the result to the type of the pointer 175 * for sign reasons. 176 * 177 * The use of _ASM_DX as the register specifier is a bit of a 178 * simplification, as gcc only cares about it as the starting point 179 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits 180 * (%ecx being the next register in gcc's x86 register sequence), and 181 * %rdx on 64 bits. 182 * 183 * Clang/LLVM cares about the size of the register, but still wants 184 * the base register for something that ends up being a pair. 185 */ 186 #define get_user(x, ptr) \ 187 ({ \ 188 int __ret_gu; \ 189 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ 190 register void *__sp asm(_ASM_SP); \ 191 __chk_user_ptr(ptr); \ 192 might_fault(); \ 193 asm volatile("call __get_user_%P4" \ 194 : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp) \ 195 : "0" (ptr), "i" (sizeof(*(ptr)))); \ 196 (x) = (__force __typeof__(*(ptr))) __val_gu; \ 197 __builtin_expect(__ret_gu, 0); \ 198 }) 199 200 #define __put_user_x(size, x, ptr, __ret_pu) \ 201 asm volatile("call __put_user_" #size : "=a" (__ret_pu) \ 202 : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx") 203 204 205 206 #ifdef CONFIG_X86_32 207 #define __put_user_asm_u64(x, addr, err, errret) \ 208 asm volatile("\n" \ 209 "1: movl %%eax,0(%2)\n" \ 210 "2: movl %%edx,4(%2)\n" \ 211 "3:" \ 212 ".section .fixup,\"ax\"\n" \ 213 "4: movl %3,%0\n" \ 214 " jmp 3b\n" \ 215 ".previous\n" \ 216 _ASM_EXTABLE(1b, 4b) \ 217 _ASM_EXTABLE(2b, 4b) \ 218 : "=r" (err) \ 219 : "A" (x), "r" (addr), "i" (errret), "0" (err)) 220 221 #define __put_user_asm_ex_u64(x, addr) \ 222 asm volatile("\n" \ 223 "1: movl %%eax,0(%1)\n" \ 224 "2: movl %%edx,4(%1)\n" \ 225 "3:" \ 226 _ASM_EXTABLE_EX(1b, 2b) \ 227 _ASM_EXTABLE_EX(2b, 3b) \ 228 : : "A" (x), "r" (addr)) 229 230 #define __put_user_x8(x, ptr, __ret_pu) \ 231 asm volatile("call __put_user_8" : "=a" (__ret_pu) \ 232 : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx") 233 #else 234 #define __put_user_asm_u64(x, ptr, retval, errret) \ 235 __put_user_asm(x, ptr, retval, "q", "", "er", errret) 236 #define __put_user_asm_ex_u64(x, addr) \ 237 __put_user_asm_ex(x, addr, "q", "", "er") 238 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu) 239 #endif 240 241 extern void __put_user_bad(void); 242 243 /* 244 * Strange magic calling convention: pointer in %ecx, 245 * value in %eax(:%edx), return value in %eax. clobbers %rbx 246 */ 247 extern void __put_user_1(void); 248 extern void __put_user_2(void); 249 extern void __put_user_4(void); 250 extern void __put_user_8(void); 251 252 /** 253 * put_user: - Write a simple value into user space. 254 * @x: Value to copy to user space. 255 * @ptr: Destination address, in user space. 256 * 257 * Context: User context only. This function may sleep if pagefaults are 258 * enabled. 259 * 260 * This macro copies a single simple value from kernel space to user 261 * space. It supports simple types like char and int, but not larger 262 * data types like structures or arrays. 263 * 264 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 265 * to the result of dereferencing @ptr. 266 * 267 * Returns zero on success, or -EFAULT on error. 268 */ 269 #define put_user(x, ptr) \ 270 ({ \ 271 int __ret_pu; \ 272 __typeof__(*(ptr)) __pu_val; \ 273 __chk_user_ptr(ptr); \ 274 might_fault(); \ 275 __pu_val = x; \ 276 switch (sizeof(*(ptr))) { \ 277 case 1: \ 278 __put_user_x(1, __pu_val, ptr, __ret_pu); \ 279 break; \ 280 case 2: \ 281 __put_user_x(2, __pu_val, ptr, __ret_pu); \ 282 break; \ 283 case 4: \ 284 __put_user_x(4, __pu_val, ptr, __ret_pu); \ 285 break; \ 286 case 8: \ 287 __put_user_x8(__pu_val, ptr, __ret_pu); \ 288 break; \ 289 default: \ 290 __put_user_x(X, __pu_val, ptr, __ret_pu); \ 291 break; \ 292 } \ 293 __builtin_expect(__ret_pu, 0); \ 294 }) 295 296 #define __put_user_size(x, ptr, size, retval, errret) \ 297 do { \ 298 retval = 0; \ 299 __chk_user_ptr(ptr); \ 300 switch (size) { \ 301 case 1: \ 302 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \ 303 break; \ 304 case 2: \ 305 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \ 306 break; \ 307 case 4: \ 308 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \ 309 break; \ 310 case 8: \ 311 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval, \ 312 errret); \ 313 break; \ 314 default: \ 315 __put_user_bad(); \ 316 } \ 317 } while (0) 318 319 /* 320 * This doesn't do __uaccess_begin/end - the exception handling 321 * around it must do that. 322 */ 323 #define __put_user_size_ex(x, ptr, size) \ 324 do { \ 325 __chk_user_ptr(ptr); \ 326 switch (size) { \ 327 case 1: \ 328 __put_user_asm_ex(x, ptr, "b", "b", "iq"); \ 329 break; \ 330 case 2: \ 331 __put_user_asm_ex(x, ptr, "w", "w", "ir"); \ 332 break; \ 333 case 4: \ 334 __put_user_asm_ex(x, ptr, "l", "k", "ir"); \ 335 break; \ 336 case 8: \ 337 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr); \ 338 break; \ 339 default: \ 340 __put_user_bad(); \ 341 } \ 342 } while (0) 343 344 #ifdef CONFIG_X86_32 345 #define __get_user_asm_u64(x, ptr, retval, errret) (x) = __get_user_bad() 346 #define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad() 347 #else 348 #define __get_user_asm_u64(x, ptr, retval, errret) \ 349 __get_user_asm(x, ptr, retval, "q", "", "=r", errret) 350 #define __get_user_asm_ex_u64(x, ptr) \ 351 __get_user_asm_ex(x, ptr, "q", "", "=r") 352 #endif 353 354 #define __get_user_size(x, ptr, size, retval, errret) \ 355 do { \ 356 retval = 0; \ 357 __chk_user_ptr(ptr); \ 358 switch (size) { \ 359 case 1: \ 360 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \ 361 break; \ 362 case 2: \ 363 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \ 364 break; \ 365 case 4: \ 366 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \ 367 break; \ 368 case 8: \ 369 __get_user_asm_u64(x, ptr, retval, errret); \ 370 break; \ 371 default: \ 372 (x) = __get_user_bad(); \ 373 } \ 374 } while (0) 375 376 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \ 377 asm volatile("\n" \ 378 "1: mov"itype" %2,%"rtype"1\n" \ 379 "2:\n" \ 380 ".section .fixup,\"ax\"\n" \ 381 "3: mov %3,%0\n" \ 382 " xor"itype" %"rtype"1,%"rtype"1\n" \ 383 " jmp 2b\n" \ 384 ".previous\n" \ 385 _ASM_EXTABLE(1b, 3b) \ 386 : "=r" (err), ltype(x) \ 387 : "m" (__m(addr)), "i" (errret), "0" (err)) 388 389 /* 390 * This doesn't do __uaccess_begin/end - the exception handling 391 * around it must do that. 392 */ 393 #define __get_user_size_ex(x, ptr, size) \ 394 do { \ 395 __chk_user_ptr(ptr); \ 396 switch (size) { \ 397 case 1: \ 398 __get_user_asm_ex(x, ptr, "b", "b", "=q"); \ 399 break; \ 400 case 2: \ 401 __get_user_asm_ex(x, ptr, "w", "w", "=r"); \ 402 break; \ 403 case 4: \ 404 __get_user_asm_ex(x, ptr, "l", "k", "=r"); \ 405 break; \ 406 case 8: \ 407 __get_user_asm_ex_u64(x, ptr); \ 408 break; \ 409 default: \ 410 (x) = __get_user_bad(); \ 411 } \ 412 } while (0) 413 414 #define __get_user_asm_ex(x, addr, itype, rtype, ltype) \ 415 asm volatile("1: mov"itype" %1,%"rtype"0\n" \ 416 "2:\n" \ 417 _ASM_EXTABLE_EX(1b, 2b) \ 418 : ltype(x) : "m" (__m(addr))) 419 420 #define __put_user_nocheck(x, ptr, size) \ 421 ({ \ 422 int __pu_err; \ 423 __uaccess_begin(); \ 424 __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \ 425 __uaccess_end(); \ 426 __builtin_expect(__pu_err, 0); \ 427 }) 428 429 #define __get_user_nocheck(x, ptr, size) \ 430 ({ \ 431 int __gu_err; \ 432 unsigned long __gu_val; \ 433 __uaccess_begin(); \ 434 __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \ 435 __uaccess_end(); \ 436 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 437 __builtin_expect(__gu_err, 0); \ 438 }) 439 440 /* FIXME: this hack is definitely wrong -AK */ 441 struct __large_struct { unsigned long buf[100]; }; 442 #define __m(x) (*(struct __large_struct __user *)(x)) 443 444 /* 445 * Tell gcc we read from memory instead of writing: this is because 446 * we do not write to any memory gcc knows about, so there are no 447 * aliasing issues. 448 */ 449 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \ 450 asm volatile("\n" \ 451 "1: mov"itype" %"rtype"1,%2\n" \ 452 "2:\n" \ 453 ".section .fixup,\"ax\"\n" \ 454 "3: mov %3,%0\n" \ 455 " jmp 2b\n" \ 456 ".previous\n" \ 457 _ASM_EXTABLE(1b, 3b) \ 458 : "=r"(err) \ 459 : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err)) 460 461 #define __put_user_asm_ex(x, addr, itype, rtype, ltype) \ 462 asm volatile("1: mov"itype" %"rtype"0,%1\n" \ 463 "2:\n" \ 464 _ASM_EXTABLE_EX(1b, 2b) \ 465 : : ltype(x), "m" (__m(addr))) 466 467 /* 468 * uaccess_try and catch 469 */ 470 #define uaccess_try do { \ 471 current_thread_info()->uaccess_err = 0; \ 472 __uaccess_begin(); \ 473 barrier(); 474 475 #define uaccess_catch(err) \ 476 __uaccess_end(); \ 477 (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0); \ 478 } while (0) 479 480 /** 481 * __get_user: - Get a simple variable from user space, with less checking. 482 * @x: Variable to store result. 483 * @ptr: Source address, in user space. 484 * 485 * Context: User context only. This function may sleep if pagefaults are 486 * enabled. 487 * 488 * This macro copies a single simple variable from user space to kernel 489 * space. It supports simple types like char and int, but not larger 490 * data types like structures or arrays. 491 * 492 * @ptr must have pointer-to-simple-variable type, and the result of 493 * dereferencing @ptr must be assignable to @x without a cast. 494 * 495 * Caller must check the pointer with access_ok() before calling this 496 * function. 497 * 498 * Returns zero on success, or -EFAULT on error. 499 * On error, the variable @x is set to zero. 500 */ 501 502 #define __get_user(x, ptr) \ 503 __get_user_nocheck((x), (ptr), sizeof(*(ptr))) 504 505 /** 506 * __put_user: - Write a simple value into user space, with less checking. 507 * @x: Value to copy to user space. 508 * @ptr: Destination address, in user space. 509 * 510 * Context: User context only. This function may sleep if pagefaults are 511 * enabled. 512 * 513 * This macro copies a single simple value from kernel space to user 514 * space. It supports simple types like char and int, but not larger 515 * data types like structures or arrays. 516 * 517 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 518 * to the result of dereferencing @ptr. 519 * 520 * Caller must check the pointer with access_ok() before calling this 521 * function. 522 * 523 * Returns zero on success, or -EFAULT on error. 524 */ 525 526 #define __put_user(x, ptr) \ 527 __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) 528 529 #define __get_user_unaligned __get_user 530 #define __put_user_unaligned __put_user 531 532 /* 533 * {get|put}_user_try and catch 534 * 535 * get_user_try { 536 * get_user_ex(...); 537 * } get_user_catch(err) 538 */ 539 #define get_user_try uaccess_try 540 #define get_user_catch(err) uaccess_catch(err) 541 542 #define get_user_ex(x, ptr) do { \ 543 unsigned long __gue_val; \ 544 __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr)))); \ 545 (x) = (__force __typeof__(*(ptr)))__gue_val; \ 546 } while (0) 547 548 #define put_user_try uaccess_try 549 #define put_user_catch(err) uaccess_catch(err) 550 551 #define put_user_ex(x, ptr) \ 552 __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) 553 554 extern unsigned long 555 copy_from_user_nmi(void *to, const void __user *from, unsigned long n); 556 extern __must_check long 557 strncpy_from_user(char *dst, const char __user *src, long count); 558 559 extern __must_check long strlen_user(const char __user *str); 560 extern __must_check long strnlen_user(const char __user *str, long n); 561 562 unsigned long __must_check clear_user(void __user *mem, unsigned long len); 563 unsigned long __must_check __clear_user(void __user *mem, unsigned long len); 564 565 extern void __cmpxchg_wrong_size(void) 566 __compiletime_error("Bad argument size for cmpxchg"); 567 568 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size) \ 569 ({ \ 570 int __ret = 0; \ 571 __typeof__(ptr) __uval = (uval); \ 572 __typeof__(*(ptr)) __old = (old); \ 573 __typeof__(*(ptr)) __new = (new); \ 574 __uaccess_begin(); \ 575 switch (size) { \ 576 case 1: \ 577 { \ 578 asm volatile("\n" \ 579 "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n" \ 580 "2:\n" \ 581 "\t.section .fixup, \"ax\"\n" \ 582 "3:\tmov %3, %0\n" \ 583 "\tjmp 2b\n" \ 584 "\t.previous\n" \ 585 _ASM_EXTABLE(1b, 3b) \ 586 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ 587 : "i" (-EFAULT), "q" (__new), "1" (__old) \ 588 : "memory" \ 589 ); \ 590 break; \ 591 } \ 592 case 2: \ 593 { \ 594 asm volatile("\n" \ 595 "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n" \ 596 "2:\n" \ 597 "\t.section .fixup, \"ax\"\n" \ 598 "3:\tmov %3, %0\n" \ 599 "\tjmp 2b\n" \ 600 "\t.previous\n" \ 601 _ASM_EXTABLE(1b, 3b) \ 602 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ 603 : "i" (-EFAULT), "r" (__new), "1" (__old) \ 604 : "memory" \ 605 ); \ 606 break; \ 607 } \ 608 case 4: \ 609 { \ 610 asm volatile("\n" \ 611 "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n" \ 612 "2:\n" \ 613 "\t.section .fixup, \"ax\"\n" \ 614 "3:\tmov %3, %0\n" \ 615 "\tjmp 2b\n" \ 616 "\t.previous\n" \ 617 _ASM_EXTABLE(1b, 3b) \ 618 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ 619 : "i" (-EFAULT), "r" (__new), "1" (__old) \ 620 : "memory" \ 621 ); \ 622 break; \ 623 } \ 624 case 8: \ 625 { \ 626 if (!IS_ENABLED(CONFIG_X86_64)) \ 627 __cmpxchg_wrong_size(); \ 628 \ 629 asm volatile("\n" \ 630 "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n" \ 631 "2:\n" \ 632 "\t.section .fixup, \"ax\"\n" \ 633 "3:\tmov %3, %0\n" \ 634 "\tjmp 2b\n" \ 635 "\t.previous\n" \ 636 _ASM_EXTABLE(1b, 3b) \ 637 : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ 638 : "i" (-EFAULT), "r" (__new), "1" (__old) \ 639 : "memory" \ 640 ); \ 641 break; \ 642 } \ 643 default: \ 644 __cmpxchg_wrong_size(); \ 645 } \ 646 __uaccess_end(); \ 647 *__uval = __old; \ 648 __ret; \ 649 }) 650 651 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new) \ 652 ({ \ 653 access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ? \ 654 __user_atomic_cmpxchg_inatomic((uval), (ptr), \ 655 (old), (new), sizeof(*(ptr))) : \ 656 -EFAULT; \ 657 }) 658 659 /* 660 * movsl can be slow when source and dest are not both 8-byte aligned 661 */ 662 #ifdef CONFIG_X86_INTEL_USERCOPY 663 extern struct movsl_mask { 664 int mask; 665 } ____cacheline_aligned_in_smp movsl_mask; 666 #endif 667 668 #define ARCH_HAS_NOCACHE_UACCESS 1 669 670 #ifdef CONFIG_X86_32 671 # include <asm/uaccess_32.h> 672 #else 673 # include <asm/uaccess_64.h> 674 #endif 675 676 unsigned long __must_check _copy_from_user(void *to, const void __user *from, 677 unsigned n); 678 unsigned long __must_check _copy_to_user(void __user *to, const void *from, 679 unsigned n); 680 681 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS 682 # define copy_user_diag __compiletime_error 683 #else 684 # define copy_user_diag __compiletime_warning 685 #endif 686 687 extern void copy_user_diag("copy_from_user() buffer size is too small") 688 copy_from_user_overflow(void); 689 extern void copy_user_diag("copy_to_user() buffer size is too small") 690 copy_to_user_overflow(void) __asm__("copy_from_user_overflow"); 691 692 #undef copy_user_diag 693 694 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS 695 696 extern void 697 __compiletime_warning("copy_from_user() buffer size is not provably correct") 698 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow"); 699 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow() 700 701 extern void 702 __compiletime_warning("copy_to_user() buffer size is not provably correct") 703 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow"); 704 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow() 705 706 #else 707 708 static inline void 709 __copy_from_user_overflow(int size, unsigned long count) 710 { 711 WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count); 712 } 713 714 #define __copy_to_user_overflow __copy_from_user_overflow 715 716 #endif 717 718 static inline unsigned long __must_check 719 copy_from_user(void *to, const void __user *from, unsigned long n) 720 { 721 int sz = __compiletime_object_size(to); 722 723 might_fault(); 724 725 kasan_check_write(to, n); 726 727 /* 728 * While we would like to have the compiler do the checking for us 729 * even in the non-constant size case, any false positives there are 730 * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even 731 * without - the [hopefully] dangerous looking nature of the warning 732 * would make people go look at the respecitive call sites over and 733 * over again just to find that there's no problem). 734 * 735 * And there are cases where it's just not realistic for the compiler 736 * to prove the count to be in range. For example when multiple call 737 * sites of a helper function - perhaps in different source files - 738 * all doing proper range checking, yet the helper function not doing 739 * so again. 740 * 741 * Therefore limit the compile time checking to the constant size 742 * case, and do only runtime checking for non-constant sizes. 743 */ 744 745 if (likely(sz < 0 || sz >= n)) 746 n = _copy_from_user(to, from, n); 747 else if(__builtin_constant_p(n)) 748 copy_from_user_overflow(); 749 else 750 __copy_from_user_overflow(sz, n); 751 752 return n; 753 } 754 755 static inline unsigned long __must_check 756 copy_to_user(void __user *to, const void *from, unsigned long n) 757 { 758 int sz = __compiletime_object_size(from); 759 760 kasan_check_read(from, n); 761 762 might_fault(); 763 764 /* See the comment in copy_from_user() above. */ 765 if (likely(sz < 0 || sz >= n)) 766 n = _copy_to_user(to, from, n); 767 else if(__builtin_constant_p(n)) 768 copy_to_user_overflow(); 769 else 770 __copy_to_user_overflow(sz, n); 771 772 return n; 773 } 774 775 #undef __copy_from_user_overflow 776 #undef __copy_to_user_overflow 777 778 /* 779 * We rely on the nested NMI work to allow atomic faults from the NMI path; the 780 * nested NMI paths are careful to preserve CR2. 781 * 782 * Caller must use pagefault_enable/disable, or run in interrupt context, 783 * and also do a uaccess_ok() check 784 */ 785 #define __copy_from_user_nmi __copy_from_user_inatomic 786 787 /* 788 * The "unsafe" user accesses aren't really "unsafe", but the naming 789 * is a big fat warning: you have to not only do the access_ok() 790 * checking before using them, but you have to surround them with the 791 * user_access_begin/end() pair. 792 */ 793 #define user_access_begin() __uaccess_begin() 794 #define user_access_end() __uaccess_end() 795 796 #define unsafe_put_user(x, ptr) \ 797 ({ \ 798 int __pu_err; \ 799 __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT); \ 800 __builtin_expect(__pu_err, 0); \ 801 }) 802 803 #define unsafe_get_user(x, ptr) \ 804 ({ \ 805 int __gu_err; \ 806 unsigned long __gu_val; \ 807 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT); \ 808 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 809 __builtin_expect(__gu_err, 0); \ 810 }) 811 812 #endif /* _ASM_X86_UACCESS_H */ 813 814