1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_X86_UACCESS_H 3 #define _ASM_X86_UACCESS_H 4 /* 5 * User space memory access functions 6 */ 7 #include <linux/compiler.h> 8 #include <linux/kasan-checks.h> 9 #include <linux/string.h> 10 #include <asm/asm.h> 11 #include <asm/page.h> 12 #include <asm/smap.h> 13 #include <asm/extable.h> 14 15 /* 16 * The fs value determines whether argument validity checking should be 17 * performed or not. If get_fs() == USER_DS, checking is performed, with 18 * get_fs() == KERNEL_DS, checking is bypassed. 19 * 20 * For historical reasons, these macros are grossly misnamed. 21 */ 22 23 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) }) 24 25 #define KERNEL_DS MAKE_MM_SEG(-1UL) 26 #define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX) 27 28 #define get_fs() (current->thread.addr_limit) 29 static inline void set_fs(mm_segment_t fs) 30 { 31 current->thread.addr_limit = fs; 32 /* On user-mode return, check fs is correct */ 33 set_thread_flag(TIF_FSCHECK); 34 } 35 36 #define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg) 37 #define user_addr_max() (current->thread.addr_limit.seg) 38 39 /* 40 * Test whether a block of memory is a valid user space address. 41 * Returns 0 if the range is valid, nonzero otherwise. 42 */ 43 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit) 44 { 45 /* 46 * If we have used "sizeof()" for the size, 47 * we know it won't overflow the limit (but 48 * it might overflow the 'addr', so it's 49 * important to subtract the size from the 50 * limit, not add it to the address). 51 */ 52 if (__builtin_constant_p(size)) 53 return unlikely(addr > limit - size); 54 55 /* Arbitrary sizes? Be careful about overflow */ 56 addr += size; 57 if (unlikely(addr < size)) 58 return true; 59 return unlikely(addr > limit); 60 } 61 62 #define __range_not_ok(addr, size, limit) \ 63 ({ \ 64 __chk_user_ptr(addr); \ 65 __chk_range_not_ok((unsigned long __force)(addr), size, limit); \ 66 }) 67 68 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP 69 static inline bool pagefault_disabled(void); 70 # define WARN_ON_IN_IRQ() \ 71 WARN_ON_ONCE(!in_task() && !pagefault_disabled()) 72 #else 73 # define WARN_ON_IN_IRQ() 74 #endif 75 76 /** 77 * access_ok - Checks if a user space pointer is valid 78 * @addr: User space pointer to start of block to check 79 * @size: Size of block to check 80 * 81 * Context: User context only. This function may sleep if pagefaults are 82 * enabled. 83 * 84 * Checks if a pointer to a block of memory in user space is valid. 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 * Return: true (nonzero) if the memory block may be valid, false (zero) 91 * if it is definitely invalid. 92 */ 93 #define access_ok(addr, size) \ 94 ({ \ 95 WARN_ON_IN_IRQ(); \ 96 likely(!__range_not_ok(addr, size, user_addr_max())); \ 97 }) 98 99 extern int __get_user_1(void); 100 extern int __get_user_2(void); 101 extern int __get_user_4(void); 102 extern int __get_user_8(void); 103 extern int __get_user_nocheck_1(void); 104 extern int __get_user_nocheck_2(void); 105 extern int __get_user_nocheck_4(void); 106 extern int __get_user_nocheck_8(void); 107 extern int __get_user_bad(void); 108 109 #define __uaccess_begin() stac() 110 #define __uaccess_end() clac() 111 #define __uaccess_begin_nospec() \ 112 ({ \ 113 stac(); \ 114 barrier_nospec(); \ 115 }) 116 117 /* 118 * This is the smallest unsigned integer type that can fit a value 119 * (up to 'long long') 120 */ 121 #define __inttype(x) __typeof__( \ 122 __typefits(x,char, \ 123 __typefits(x,short, \ 124 __typefits(x,int, \ 125 __typefits(x,long,0ULL))))) 126 127 #define __typefits(x,type,not) \ 128 __builtin_choose_expr(sizeof(x)<=sizeof(type),(unsigned type)0,not) 129 130 /* 131 * This is used for both get_user() and __get_user() to expand to 132 * the proper special function call that has odd calling conventions 133 * due to returning both a value and an error, and that depends on 134 * the size of the pointer passed in. 135 * 136 * Careful: we have to cast the result to the type of the pointer 137 * for sign reasons. 138 * 139 * The use of _ASM_DX as the register specifier is a bit of a 140 * simplification, as gcc only cares about it as the starting point 141 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits 142 * (%ecx being the next register in gcc's x86 register sequence), and 143 * %rdx on 64 bits. 144 * 145 * Clang/LLVM cares about the size of the register, but still wants 146 * the base register for something that ends up being a pair. 147 */ 148 #define do_get_user_call(fn,x,ptr) \ 149 ({ \ 150 int __ret_gu; \ 151 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ 152 __chk_user_ptr(ptr); \ 153 asm volatile("call __" #fn "_%P4" \ 154 : "=a" (__ret_gu), "=r" (__val_gu), \ 155 ASM_CALL_CONSTRAINT \ 156 : "0" (ptr), "i" (sizeof(*(ptr)))); \ 157 (x) = (__force __typeof__(*(ptr))) __val_gu; \ 158 __builtin_expect(__ret_gu, 0); \ 159 }) 160 161 /** 162 * get_user - Get a simple variable from user space. 163 * @x: Variable to store result. 164 * @ptr: Source address, in user space. 165 * 166 * Context: User context only. This function may sleep if pagefaults are 167 * enabled. 168 * 169 * This macro copies a single simple variable from user space to kernel 170 * space. It supports simple types like char and int, but not larger 171 * data types like structures or arrays. 172 * 173 * @ptr must have pointer-to-simple-variable type, and the result of 174 * dereferencing @ptr must be assignable to @x without a cast. 175 * 176 * Return: zero on success, or -EFAULT on error. 177 * On error, the variable @x is set to zero. 178 */ 179 #define get_user(x,ptr) ({ might_fault(); do_get_user_call(get_user,x,ptr); }) 180 181 /** 182 * __get_user - Get a simple variable from user space, with less checking. 183 * @x: Variable to store result. 184 * @ptr: Source address, in user space. 185 * 186 * Context: User context only. This function may sleep if pagefaults are 187 * enabled. 188 * 189 * This macro copies a single simple variable from user space to kernel 190 * space. It supports simple types like char and int, but not larger 191 * data types like structures or arrays. 192 * 193 * @ptr must have pointer-to-simple-variable type, and the result of 194 * dereferencing @ptr must be assignable to @x without a cast. 195 * 196 * Caller must check the pointer with access_ok() before calling this 197 * function. 198 * 199 * Return: zero on success, or -EFAULT on error. 200 * On error, the variable @x is set to zero. 201 */ 202 #define __get_user(x,ptr) do_get_user_call(get_user_nocheck,x,ptr) 203 204 205 #ifdef CONFIG_X86_32 206 #define __put_user_goto_u64(x, addr, label) \ 207 asm_volatile_goto("\n" \ 208 "1: movl %%eax,0(%1)\n" \ 209 "2: movl %%edx,4(%1)\n" \ 210 _ASM_EXTABLE_UA(1b, %l2) \ 211 _ASM_EXTABLE_UA(2b, %l2) \ 212 : : "A" (x), "r" (addr) \ 213 : : label) 214 215 #else 216 #define __put_user_goto_u64(x, ptr, label) \ 217 __put_user_goto(x, ptr, "q", "er", label) 218 #endif 219 220 extern void __put_user_bad(void); 221 222 /* 223 * Strange magic calling convention: pointer in %ecx, 224 * value in %eax(:%edx), return value in %ecx. clobbers %rbx 225 */ 226 extern void __put_user_1(void); 227 extern void __put_user_2(void); 228 extern void __put_user_4(void); 229 extern void __put_user_8(void); 230 extern void __put_user_nocheck_1(void); 231 extern void __put_user_nocheck_2(void); 232 extern void __put_user_nocheck_4(void); 233 extern void __put_user_nocheck_8(void); 234 235 #define do_put_user_call(fn,x,ptr) \ 236 ({ \ 237 int __ret_pu; \ 238 register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX); \ 239 __chk_user_ptr(ptr); \ 240 __val_pu = (x); \ 241 asm volatile("call __" #fn "_%P[size]" \ 242 : "=c" (__ret_pu), \ 243 ASM_CALL_CONSTRAINT \ 244 : "0" (ptr), \ 245 "r" (__val_pu), \ 246 [size] "i" (sizeof(*(ptr))) \ 247 :"ebx"); \ 248 __builtin_expect(__ret_pu, 0); \ 249 }) 250 251 /** 252 * put_user - Write a simple value into user space. 253 * @x: Value to copy to user space. 254 * @ptr: Destination address, in user space. 255 * 256 * Context: User context only. This function may sleep if pagefaults are 257 * enabled. 258 * 259 * This macro copies a single simple value from kernel space to user 260 * space. It supports simple types like char and int, but not larger 261 * data types like structures or arrays. 262 * 263 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 264 * to the result of dereferencing @ptr. 265 * 266 * Return: zero on success, or -EFAULT on error. 267 */ 268 #define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); }) 269 270 /** 271 * __put_user - Write a simple value into user space, with less checking. 272 * @x: Value to copy to user space. 273 * @ptr: Destination address, in user space. 274 * 275 * Context: User context only. This function may sleep if pagefaults are 276 * enabled. 277 * 278 * This macro copies a single simple value from kernel space to user 279 * space. It supports simple types like char and int, but not larger 280 * data types like structures or arrays. 281 * 282 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 283 * to the result of dereferencing @ptr. 284 * 285 * Caller must check the pointer with access_ok() before calling this 286 * function. 287 * 288 * Return: zero on success, or -EFAULT on error. 289 */ 290 #define __put_user(x, ptr) do_put_user_call(put_user_nocheck,x,ptr) 291 292 #define __put_user_size(x, ptr, size, label) \ 293 do { \ 294 __chk_user_ptr(ptr); \ 295 switch (size) { \ 296 case 1: \ 297 __put_user_goto(x, ptr, "b", "iq", label); \ 298 break; \ 299 case 2: \ 300 __put_user_goto(x, ptr, "w", "ir", label); \ 301 break; \ 302 case 4: \ 303 __put_user_goto(x, ptr, "l", "ir", label); \ 304 break; \ 305 case 8: \ 306 __put_user_goto_u64(x, ptr, label); \ 307 break; \ 308 default: \ 309 __put_user_bad(); \ 310 } \ 311 } while (0) 312 313 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 314 315 #ifdef CONFIG_X86_32 316 #define __get_user_asm_u64(x, ptr, label) do { \ 317 unsigned int __gu_low, __gu_high; \ 318 const unsigned int __user *__gu_ptr; \ 319 __gu_ptr = (const void __user *)(ptr); \ 320 __get_user_asm(__gu_low, ptr, "l", "=r", label); \ 321 __get_user_asm(__gu_high, ptr+1, "l", "=r", label); \ 322 (x) = ((unsigned long long)__gu_high << 32) | __gu_low; \ 323 } while (0) 324 #else 325 #define __get_user_asm_u64(x, ptr, label) \ 326 __get_user_asm(x, ptr, "q", "=r", label) 327 #endif 328 329 #define __get_user_size(x, ptr, size, label) \ 330 do { \ 331 __chk_user_ptr(ptr); \ 332 switch (size) { \ 333 unsigned char x_u8__; \ 334 case 1: \ 335 __get_user_asm(x_u8__, ptr, "b", "=q", label); \ 336 (x) = x_u8__; \ 337 break; \ 338 case 2: \ 339 __get_user_asm(x, ptr, "w", "=r", label); \ 340 break; \ 341 case 4: \ 342 __get_user_asm(x, ptr, "l", "=r", label); \ 343 break; \ 344 case 8: \ 345 __get_user_asm_u64(x, ptr, label); \ 346 break; \ 347 default: \ 348 (x) = __get_user_bad(); \ 349 } \ 350 } while (0) 351 352 #define __get_user_asm(x, addr, itype, ltype, label) \ 353 asm_volatile_goto("\n" \ 354 "1: mov"itype" %[umem],%[output]\n" \ 355 _ASM_EXTABLE_UA(1b, %l2) \ 356 : [output] ltype(x) \ 357 : [umem] "m" (__m(addr)) \ 358 : : label) 359 360 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT 361 362 #ifdef CONFIG_X86_32 363 #define __get_user_asm_u64(x, ptr, retval) \ 364 ({ \ 365 __typeof__(ptr) __ptr = (ptr); \ 366 asm volatile("\n" \ 367 "1: movl %[lowbits],%%eax\n" \ 368 "2: movl %[highbits],%%edx\n" \ 369 "3:\n" \ 370 ".section .fixup,\"ax\"\n" \ 371 "4: mov %[efault],%[errout]\n" \ 372 " xorl %%eax,%%eax\n" \ 373 " xorl %%edx,%%edx\n" \ 374 " jmp 3b\n" \ 375 ".previous\n" \ 376 _ASM_EXTABLE_UA(1b, 4b) \ 377 _ASM_EXTABLE_UA(2b, 4b) \ 378 : [errout] "=r" (retval), \ 379 [output] "=&A"(x) \ 380 : [lowbits] "m" (__m(__ptr)), \ 381 [highbits] "m" __m(((u32 __user *)(__ptr)) + 1), \ 382 [efault] "i" (-EFAULT), "0" (retval)); \ 383 }) 384 385 #else 386 #define __get_user_asm_u64(x, ptr, retval) \ 387 __get_user_asm(x, ptr, retval, "q", "=r") 388 #endif 389 390 #define __get_user_size(x, ptr, size, retval) \ 391 do { \ 392 unsigned char x_u8__; \ 393 \ 394 retval = 0; \ 395 __chk_user_ptr(ptr); \ 396 switch (size) { \ 397 case 1: \ 398 __get_user_asm(x_u8__, ptr, retval, "b", "=q"); \ 399 (x) = x_u8__; \ 400 break; \ 401 case 2: \ 402 __get_user_asm(x, ptr, retval, "w", "=r"); \ 403 break; \ 404 case 4: \ 405 __get_user_asm(x, ptr, retval, "l", "=r"); \ 406 break; \ 407 case 8: \ 408 __get_user_asm_u64(x, ptr, retval); \ 409 break; \ 410 default: \ 411 (x) = __get_user_bad(); \ 412 } \ 413 } while (0) 414 415 #define __get_user_asm(x, addr, err, itype, ltype) \ 416 asm volatile("\n" \ 417 "1: mov"itype" %[umem],%[output]\n" \ 418 "2:\n" \ 419 ".section .fixup,\"ax\"\n" \ 420 "3: mov %[efault],%[errout]\n" \ 421 " xorl %k[output],%k[output]\n" \ 422 " jmp 2b\n" \ 423 ".previous\n" \ 424 _ASM_EXTABLE_UA(1b, 3b) \ 425 : [errout] "=r" (err), \ 426 [output] ltype(x) \ 427 : [umem] "m" (__m(addr)), \ 428 [efault] "i" (-EFAULT), "0" (err)) 429 430 #endif // CONFIG_CC_ASM_GOTO_OUTPUT 431 432 /* FIXME: this hack is definitely wrong -AK */ 433 struct __large_struct { unsigned long buf[100]; }; 434 #define __m(x) (*(struct __large_struct __user *)(x)) 435 436 /* 437 * Tell gcc we read from memory instead of writing: this is because 438 * we do not write to any memory gcc knows about, so there are no 439 * aliasing issues. 440 */ 441 #define __put_user_goto(x, addr, itype, ltype, label) \ 442 asm_volatile_goto("\n" \ 443 "1: mov"itype" %0,%1\n" \ 444 _ASM_EXTABLE_UA(1b, %l2) \ 445 : : ltype(x), "m" (__m(addr)) \ 446 : : label) 447 448 extern unsigned long 449 copy_from_user_nmi(void *to, const void __user *from, unsigned long n); 450 extern __must_check long 451 strncpy_from_user(char *dst, const char __user *src, long count); 452 453 extern __must_check long strnlen_user(const char __user *str, long n); 454 455 unsigned long __must_check clear_user(void __user *mem, unsigned long len); 456 unsigned long __must_check __clear_user(void __user *mem, unsigned long len); 457 458 #ifdef CONFIG_ARCH_HAS_COPY_MC 459 unsigned long __must_check 460 copy_mc_to_kernel(void *to, const void *from, unsigned len); 461 #define copy_mc_to_kernel copy_mc_to_kernel 462 463 unsigned long __must_check 464 copy_mc_to_user(void *to, const void *from, unsigned len); 465 #endif 466 467 /* 468 * movsl can be slow when source and dest are not both 8-byte aligned 469 */ 470 #ifdef CONFIG_X86_INTEL_USERCOPY 471 extern struct movsl_mask { 472 int mask; 473 } ____cacheline_aligned_in_smp movsl_mask; 474 #endif 475 476 #define ARCH_HAS_NOCACHE_UACCESS 1 477 478 #ifdef CONFIG_X86_32 479 # include <asm/uaccess_32.h> 480 #else 481 # include <asm/uaccess_64.h> 482 #endif 483 484 /* 485 * The "unsafe" user accesses aren't really "unsafe", but the naming 486 * is a big fat warning: you have to not only do the access_ok() 487 * checking before using them, but you have to surround them with the 488 * user_access_begin/end() pair. 489 */ 490 static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len) 491 { 492 if (unlikely(!access_ok(ptr,len))) 493 return 0; 494 __uaccess_begin_nospec(); 495 return 1; 496 } 497 #define user_access_begin(a,b) user_access_begin(a,b) 498 #define user_access_end() __uaccess_end() 499 500 #define user_access_save() smap_save() 501 #define user_access_restore(x) smap_restore(x) 502 503 #define unsafe_put_user(x, ptr, label) \ 504 __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label) 505 506 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 507 #define unsafe_get_user(x, ptr, err_label) \ 508 do { \ 509 __inttype(*(ptr)) __gu_val; \ 510 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), err_label); \ 511 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 512 } while (0) 513 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT 514 #define unsafe_get_user(x, ptr, err_label) \ 515 do { \ 516 int __gu_err; \ 517 __inttype(*(ptr)) __gu_val; \ 518 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err); \ 519 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 520 if (unlikely(__gu_err)) goto err_label; \ 521 } while (0) 522 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT 523 524 /* 525 * We want the unsafe accessors to always be inlined and use 526 * the error labels - thus the macro games. 527 */ 528 #define unsafe_copy_loop(dst, src, len, type, label) \ 529 while (len >= sizeof(type)) { \ 530 unsafe_put_user(*(type *)(src),(type __user *)(dst),label); \ 531 dst += sizeof(type); \ 532 src += sizeof(type); \ 533 len -= sizeof(type); \ 534 } 535 536 #define unsafe_copy_to_user(_dst,_src,_len,label) \ 537 do { \ 538 char __user *__ucu_dst = (_dst); \ 539 const char *__ucu_src = (_src); \ 540 size_t __ucu_len = (_len); \ 541 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \ 542 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \ 543 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \ 544 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \ 545 } while (0) 546 547 #define HAVE_GET_KERNEL_NOFAULT 548 549 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 550 #define __get_kernel_nofault(dst, src, type, err_label) \ 551 __get_user_size(*((type *)(dst)), (__force type __user *)(src), \ 552 sizeof(type), err_label) 553 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT 554 #define __get_kernel_nofault(dst, src, type, err_label) \ 555 do { \ 556 int __kr_err; \ 557 \ 558 __get_user_size(*((type *)(dst)), (__force type __user *)(src), \ 559 sizeof(type), __kr_err); \ 560 if (unlikely(__kr_err)) \ 561 goto err_label; \ 562 } while (0) 563 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT 564 565 #define __put_kernel_nofault(dst, src, type, err_label) \ 566 __put_user_size(*((type *)(src)), (__force type __user *)(dst), \ 567 sizeof(type), err_label) 568 569 #endif /* _ASM_X86_UACCESS_H */ 570 571