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 * Test whether a block of memory is a valid user space address. 17 * Returns 0 if the range is valid, nonzero otherwise. 18 */ 19 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit) 20 { 21 /* 22 * If we have used "sizeof()" for the size, 23 * we know it won't overflow the limit (but 24 * it might overflow the 'addr', so it's 25 * important to subtract the size from the 26 * limit, not add it to the address). 27 */ 28 if (__builtin_constant_p(size)) 29 return unlikely(addr > limit - size); 30 31 /* Arbitrary sizes? Be careful about overflow */ 32 addr += size; 33 if (unlikely(addr < size)) 34 return true; 35 return unlikely(addr > limit); 36 } 37 38 #define __range_not_ok(addr, size, limit) \ 39 ({ \ 40 __chk_user_ptr(addr); \ 41 __chk_range_not_ok((unsigned long __force)(addr), size, limit); \ 42 }) 43 44 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP 45 static inline bool pagefault_disabled(void); 46 # define WARN_ON_IN_IRQ() \ 47 WARN_ON_ONCE(!in_task() && !pagefault_disabled()) 48 #else 49 # define WARN_ON_IN_IRQ() 50 #endif 51 52 /** 53 * access_ok - Checks if a user space pointer is valid 54 * @addr: User space pointer to start of block to check 55 * @size: Size of block to check 56 * 57 * Context: User context only. This function may sleep if pagefaults are 58 * enabled. 59 * 60 * Checks if a pointer to a block of memory in user space is valid. 61 * 62 * Note that, depending on architecture, this function probably just 63 * checks that the pointer is in the user space range - after calling 64 * this function, memory access functions may still return -EFAULT. 65 * 66 * Return: true (nonzero) if the memory block may be valid, false (zero) 67 * if it is definitely invalid. 68 */ 69 #define access_ok(addr, size) \ 70 ({ \ 71 WARN_ON_IN_IRQ(); \ 72 likely(!__range_not_ok(addr, size, TASK_SIZE_MAX)); \ 73 }) 74 75 extern int __get_user_1(void); 76 extern int __get_user_2(void); 77 extern int __get_user_4(void); 78 extern int __get_user_8(void); 79 extern int __get_user_nocheck_1(void); 80 extern int __get_user_nocheck_2(void); 81 extern int __get_user_nocheck_4(void); 82 extern int __get_user_nocheck_8(void); 83 extern int __get_user_bad(void); 84 85 #define __uaccess_begin() stac() 86 #define __uaccess_end() clac() 87 #define __uaccess_begin_nospec() \ 88 ({ \ 89 stac(); \ 90 barrier_nospec(); \ 91 }) 92 93 /* 94 * This is the smallest unsigned integer type that can fit a value 95 * (up to 'long long') 96 */ 97 #define __inttype(x) __typeof__( \ 98 __typefits(x,char, \ 99 __typefits(x,short, \ 100 __typefits(x,int, \ 101 __typefits(x,long,0ULL))))) 102 103 #define __typefits(x,type,not) \ 104 __builtin_choose_expr(sizeof(x)<=sizeof(type),(unsigned type)0,not) 105 106 /* 107 * This is used for both get_user() and __get_user() to expand to 108 * the proper special function call that has odd calling conventions 109 * due to returning both a value and an error, and that depends on 110 * the size of the pointer passed in. 111 * 112 * Careful: we have to cast the result to the type of the pointer 113 * for sign reasons. 114 * 115 * The use of _ASM_DX as the register specifier is a bit of a 116 * simplification, as gcc only cares about it as the starting point 117 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits 118 * (%ecx being the next register in gcc's x86 register sequence), and 119 * %rdx on 64 bits. 120 * 121 * Clang/LLVM cares about the size of the register, but still wants 122 * the base register for something that ends up being a pair. 123 */ 124 #define do_get_user_call(fn,x,ptr) \ 125 ({ \ 126 int __ret_gu; \ 127 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ 128 __chk_user_ptr(ptr); \ 129 asm volatile("call __" #fn "_%P4" \ 130 : "=a" (__ret_gu), "=r" (__val_gu), \ 131 ASM_CALL_CONSTRAINT \ 132 : "0" (ptr), "i" (sizeof(*(ptr)))); \ 133 (x) = (__force __typeof__(*(ptr))) __val_gu; \ 134 __builtin_expect(__ret_gu, 0); \ 135 }) 136 137 /** 138 * get_user - Get a simple variable from user space. 139 * @x: Variable to store result. 140 * @ptr: Source address, in user space. 141 * 142 * Context: User context only. This function may sleep if pagefaults are 143 * enabled. 144 * 145 * This macro copies a single simple variable from user space to kernel 146 * space. It supports simple types like char and int, but not larger 147 * data types like structures or arrays. 148 * 149 * @ptr must have pointer-to-simple-variable type, and the result of 150 * dereferencing @ptr must be assignable to @x without a cast. 151 * 152 * Return: zero on success, or -EFAULT on error. 153 * On error, the variable @x is set to zero. 154 */ 155 #define get_user(x,ptr) ({ might_fault(); do_get_user_call(get_user,x,ptr); }) 156 157 /** 158 * __get_user - Get a simple variable from user space, with less checking. 159 * @x: Variable to store result. 160 * @ptr: Source address, in user space. 161 * 162 * Context: User context only. This function may sleep if pagefaults are 163 * enabled. 164 * 165 * This macro copies a single simple variable from user space to kernel 166 * space. It supports simple types like char and int, but not larger 167 * data types like structures or arrays. 168 * 169 * @ptr must have pointer-to-simple-variable type, and the result of 170 * dereferencing @ptr must be assignable to @x without a cast. 171 * 172 * Caller must check the pointer with access_ok() before calling this 173 * function. 174 * 175 * Return: zero on success, or -EFAULT on error. 176 * On error, the variable @x is set to zero. 177 */ 178 #define __get_user(x,ptr) do_get_user_call(get_user_nocheck,x,ptr) 179 180 181 #ifdef CONFIG_X86_32 182 #define __put_user_goto_u64(x, addr, label) \ 183 asm_volatile_goto("\n" \ 184 "1: movl %%eax,0(%1)\n" \ 185 "2: movl %%edx,4(%1)\n" \ 186 _ASM_EXTABLE_UA(1b, %l2) \ 187 _ASM_EXTABLE_UA(2b, %l2) \ 188 : : "A" (x), "r" (addr) \ 189 : : label) 190 191 #else 192 #define __put_user_goto_u64(x, ptr, label) \ 193 __put_user_goto(x, ptr, "q", "er", label) 194 #endif 195 196 extern void __put_user_bad(void); 197 198 /* 199 * Strange magic calling convention: pointer in %ecx, 200 * value in %eax(:%edx), return value in %ecx. clobbers %rbx 201 */ 202 extern void __put_user_1(void); 203 extern void __put_user_2(void); 204 extern void __put_user_4(void); 205 extern void __put_user_8(void); 206 extern void __put_user_nocheck_1(void); 207 extern void __put_user_nocheck_2(void); 208 extern void __put_user_nocheck_4(void); 209 extern void __put_user_nocheck_8(void); 210 211 #define do_put_user_call(fn,x,ptr) \ 212 ({ \ 213 int __ret_pu; \ 214 register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX); \ 215 __chk_user_ptr(ptr); \ 216 __val_pu = (x); \ 217 asm volatile("call __" #fn "_%P[size]" \ 218 : "=c" (__ret_pu), \ 219 ASM_CALL_CONSTRAINT \ 220 : "0" (ptr), \ 221 "r" (__val_pu), \ 222 [size] "i" (sizeof(*(ptr))) \ 223 :"ebx"); \ 224 __builtin_expect(__ret_pu, 0); \ 225 }) 226 227 /** 228 * put_user - Write a simple value into user space. 229 * @x: Value to copy to user space. 230 * @ptr: Destination address, in user space. 231 * 232 * Context: User context only. This function may sleep if pagefaults are 233 * enabled. 234 * 235 * This macro copies a single simple value from kernel space to user 236 * space. It supports simple types like char and int, but not larger 237 * data types like structures or arrays. 238 * 239 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 240 * to the result of dereferencing @ptr. 241 * 242 * Return: zero on success, or -EFAULT on error. 243 */ 244 #define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); }) 245 246 /** 247 * __put_user - Write a simple value into user space, with less checking. 248 * @x: Value to copy to user space. 249 * @ptr: Destination address, in user space. 250 * 251 * Context: User context only. This function may sleep if pagefaults are 252 * enabled. 253 * 254 * This macro copies a single simple value from kernel space to user 255 * space. It supports simple types like char and int, but not larger 256 * data types like structures or arrays. 257 * 258 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 259 * to the result of dereferencing @ptr. 260 * 261 * Caller must check the pointer with access_ok() before calling this 262 * function. 263 * 264 * Return: zero on success, or -EFAULT on error. 265 */ 266 #define __put_user(x, ptr) do_put_user_call(put_user_nocheck,x,ptr) 267 268 #define __put_user_size(x, ptr, size, label) \ 269 do { \ 270 __chk_user_ptr(ptr); \ 271 switch (size) { \ 272 case 1: \ 273 __put_user_goto(x, ptr, "b", "iq", label); \ 274 break; \ 275 case 2: \ 276 __put_user_goto(x, ptr, "w", "ir", label); \ 277 break; \ 278 case 4: \ 279 __put_user_goto(x, ptr, "l", "ir", label); \ 280 break; \ 281 case 8: \ 282 __put_user_goto_u64(x, ptr, label); \ 283 break; \ 284 default: \ 285 __put_user_bad(); \ 286 } \ 287 } while (0) 288 289 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 290 291 #ifdef CONFIG_X86_32 292 #define __get_user_asm_u64(x, ptr, label) do { \ 293 unsigned int __gu_low, __gu_high; \ 294 const unsigned int __user *__gu_ptr; \ 295 __gu_ptr = (const void __user *)(ptr); \ 296 __get_user_asm(__gu_low, ptr, "l", "=r", label); \ 297 __get_user_asm(__gu_high, ptr+1, "l", "=r", label); \ 298 (x) = ((unsigned long long)__gu_high << 32) | __gu_low; \ 299 } while (0) 300 #else 301 #define __get_user_asm_u64(x, ptr, label) \ 302 __get_user_asm(x, ptr, "q", "=r", label) 303 #endif 304 305 #define __get_user_size(x, ptr, size, label) \ 306 do { \ 307 __chk_user_ptr(ptr); \ 308 switch (size) { \ 309 unsigned char x_u8__; \ 310 case 1: \ 311 __get_user_asm(x_u8__, ptr, "b", "=q", label); \ 312 (x) = x_u8__; \ 313 break; \ 314 case 2: \ 315 __get_user_asm(x, ptr, "w", "=r", label); \ 316 break; \ 317 case 4: \ 318 __get_user_asm(x, ptr, "l", "=r", label); \ 319 break; \ 320 case 8: \ 321 __get_user_asm_u64(x, ptr, label); \ 322 break; \ 323 default: \ 324 (x) = __get_user_bad(); \ 325 } \ 326 } while (0) 327 328 #define __get_user_asm(x, addr, itype, ltype, label) \ 329 asm_volatile_goto("\n" \ 330 "1: mov"itype" %[umem],%[output]\n" \ 331 _ASM_EXTABLE_UA(1b, %l2) \ 332 : [output] ltype(x) \ 333 : [umem] "m" (__m(addr)) \ 334 : : label) 335 336 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT 337 338 #ifdef CONFIG_X86_32 339 #define __get_user_asm_u64(x, ptr, retval) \ 340 ({ \ 341 __typeof__(ptr) __ptr = (ptr); \ 342 asm volatile("\n" \ 343 "1: movl %[lowbits],%%eax\n" \ 344 "2: movl %[highbits],%%edx\n" \ 345 "3:\n" \ 346 ".section .fixup,\"ax\"\n" \ 347 "4: mov %[efault],%[errout]\n" \ 348 " xorl %%eax,%%eax\n" \ 349 " xorl %%edx,%%edx\n" \ 350 " jmp 3b\n" \ 351 ".previous\n" \ 352 _ASM_EXTABLE_UA(1b, 4b) \ 353 _ASM_EXTABLE_UA(2b, 4b) \ 354 : [errout] "=r" (retval), \ 355 [output] "=&A"(x) \ 356 : [lowbits] "m" (__m(__ptr)), \ 357 [highbits] "m" __m(((u32 __user *)(__ptr)) + 1), \ 358 [efault] "i" (-EFAULT), "0" (retval)); \ 359 }) 360 361 #else 362 #define __get_user_asm_u64(x, ptr, retval) \ 363 __get_user_asm(x, ptr, retval, "q", "=r") 364 #endif 365 366 #define __get_user_size(x, ptr, size, retval) \ 367 do { \ 368 unsigned char x_u8__; \ 369 \ 370 retval = 0; \ 371 __chk_user_ptr(ptr); \ 372 switch (size) { \ 373 case 1: \ 374 __get_user_asm(x_u8__, ptr, retval, "b", "=q"); \ 375 (x) = x_u8__; \ 376 break; \ 377 case 2: \ 378 __get_user_asm(x, ptr, retval, "w", "=r"); \ 379 break; \ 380 case 4: \ 381 __get_user_asm(x, ptr, retval, "l", "=r"); \ 382 break; \ 383 case 8: \ 384 __get_user_asm_u64(x, ptr, retval); \ 385 break; \ 386 default: \ 387 (x) = __get_user_bad(); \ 388 } \ 389 } while (0) 390 391 #define __get_user_asm(x, addr, err, itype, ltype) \ 392 asm volatile("\n" \ 393 "1: mov"itype" %[umem],%[output]\n" \ 394 "2:\n" \ 395 ".section .fixup,\"ax\"\n" \ 396 "3: mov %[efault],%[errout]\n" \ 397 " xorl %k[output],%k[output]\n" \ 398 " jmp 2b\n" \ 399 ".previous\n" \ 400 _ASM_EXTABLE_UA(1b, 3b) \ 401 : [errout] "=r" (err), \ 402 [output] ltype(x) \ 403 : [umem] "m" (__m(addr)), \ 404 [efault] "i" (-EFAULT), "0" (err)) 405 406 #endif // CONFIG_CC_ASM_GOTO_OUTPUT 407 408 /* FIXME: this hack is definitely wrong -AK */ 409 struct __large_struct { unsigned long buf[100]; }; 410 #define __m(x) (*(struct __large_struct __user *)(x)) 411 412 /* 413 * Tell gcc we read from memory instead of writing: this is because 414 * we do not write to any memory gcc knows about, so there are no 415 * aliasing issues. 416 */ 417 #define __put_user_goto(x, addr, itype, ltype, label) \ 418 asm_volatile_goto("\n" \ 419 "1: mov"itype" %0,%1\n" \ 420 _ASM_EXTABLE_UA(1b, %l2) \ 421 : : ltype(x), "m" (__m(addr)) \ 422 : : label) 423 424 extern unsigned long 425 copy_from_user_nmi(void *to, const void __user *from, unsigned long n); 426 extern __must_check long 427 strncpy_from_user(char *dst, const char __user *src, long count); 428 429 extern __must_check long strnlen_user(const char __user *str, long n); 430 431 unsigned long __must_check clear_user(void __user *mem, unsigned long len); 432 unsigned long __must_check __clear_user(void __user *mem, unsigned long len); 433 434 #ifdef CONFIG_ARCH_HAS_COPY_MC 435 unsigned long __must_check 436 copy_mc_to_kernel(void *to, const void *from, unsigned len); 437 #define copy_mc_to_kernel copy_mc_to_kernel 438 439 unsigned long __must_check 440 copy_mc_to_user(void *to, const void *from, unsigned len); 441 #endif 442 443 /* 444 * movsl can be slow when source and dest are not both 8-byte aligned 445 */ 446 #ifdef CONFIG_X86_INTEL_USERCOPY 447 extern struct movsl_mask { 448 int mask; 449 } ____cacheline_aligned_in_smp movsl_mask; 450 #endif 451 452 #define ARCH_HAS_NOCACHE_UACCESS 1 453 454 #ifdef CONFIG_X86_32 455 # include <asm/uaccess_32.h> 456 #else 457 # include <asm/uaccess_64.h> 458 #endif 459 460 /* 461 * The "unsafe" user accesses aren't really "unsafe", but the naming 462 * is a big fat warning: you have to not only do the access_ok() 463 * checking before using them, but you have to surround them with the 464 * user_access_begin/end() pair. 465 */ 466 static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len) 467 { 468 if (unlikely(!access_ok(ptr,len))) 469 return 0; 470 __uaccess_begin_nospec(); 471 return 1; 472 } 473 #define user_access_begin(a,b) user_access_begin(a,b) 474 #define user_access_end() __uaccess_end() 475 476 #define user_access_save() smap_save() 477 #define user_access_restore(x) smap_restore(x) 478 479 #define unsafe_put_user(x, ptr, label) \ 480 __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label) 481 482 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 483 #define unsafe_get_user(x, ptr, err_label) \ 484 do { \ 485 __inttype(*(ptr)) __gu_val; \ 486 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), err_label); \ 487 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 488 } while (0) 489 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT 490 #define unsafe_get_user(x, ptr, err_label) \ 491 do { \ 492 int __gu_err; \ 493 __inttype(*(ptr)) __gu_val; \ 494 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err); \ 495 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 496 if (unlikely(__gu_err)) goto err_label; \ 497 } while (0) 498 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT 499 500 /* 501 * We want the unsafe accessors to always be inlined and use 502 * the error labels - thus the macro games. 503 */ 504 #define unsafe_copy_loop(dst, src, len, type, label) \ 505 while (len >= sizeof(type)) { \ 506 unsafe_put_user(*(type *)(src),(type __user *)(dst),label); \ 507 dst += sizeof(type); \ 508 src += sizeof(type); \ 509 len -= sizeof(type); \ 510 } 511 512 #define unsafe_copy_to_user(_dst,_src,_len,label) \ 513 do { \ 514 char __user *__ucu_dst = (_dst); \ 515 const char *__ucu_src = (_src); \ 516 size_t __ucu_len = (_len); \ 517 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \ 518 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \ 519 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \ 520 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \ 521 } while (0) 522 523 #define HAVE_GET_KERNEL_NOFAULT 524 525 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 526 #define __get_kernel_nofault(dst, src, type, err_label) \ 527 __get_user_size(*((type *)(dst)), (__force type __user *)(src), \ 528 sizeof(type), err_label) 529 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT 530 #define __get_kernel_nofault(dst, src, type, err_label) \ 531 do { \ 532 int __kr_err; \ 533 \ 534 __get_user_size(*((type *)(dst)), (__force type __user *)(src), \ 535 sizeof(type), __kr_err); \ 536 if (unlikely(__kr_err)) \ 537 goto err_label; \ 538 } while (0) 539 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT 540 541 #define __put_kernel_nofault(dst, src, type, err_label) \ 542 __put_user_size(*((type *)(src)), (__force type __user *)(dst), \ 543 sizeof(type), err_label) 544 545 #endif /* _ASM_X86_UACCESS_H */ 546 547