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 /* 212 * ptr must be evaluated and assigned to the temporary __ptr_pu before 213 * the assignment of x to __val_pu, to avoid any function calls 214 * involved in the ptr expression (possibly implicitly generated due 215 * to KASAN) from clobbering %ax. 216 */ 217 #define do_put_user_call(fn,x,ptr) \ 218 ({ \ 219 int __ret_pu; \ 220 void __user *__ptr_pu; \ 221 register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX); \ 222 __chk_user_ptr(ptr); \ 223 __ptr_pu = (ptr); \ 224 __val_pu = (x); \ 225 asm volatile("call __" #fn "_%P[size]" \ 226 : "=c" (__ret_pu), \ 227 ASM_CALL_CONSTRAINT \ 228 : "0" (__ptr_pu), \ 229 "r" (__val_pu), \ 230 [size] "i" (sizeof(*(ptr))) \ 231 :"ebx"); \ 232 __builtin_expect(__ret_pu, 0); \ 233 }) 234 235 /** 236 * put_user - Write a simple value into user space. 237 * @x: Value to copy to user space. 238 * @ptr: Destination address, in user space. 239 * 240 * Context: User context only. This function may sleep if pagefaults are 241 * enabled. 242 * 243 * This macro copies a single simple value from kernel space to user 244 * space. It supports simple types like char and int, but not larger 245 * data types like structures or arrays. 246 * 247 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 248 * to the result of dereferencing @ptr. 249 * 250 * Return: zero on success, or -EFAULT on error. 251 */ 252 #define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); }) 253 254 /** 255 * __put_user - Write a simple value into user space, with less checking. 256 * @x: Value to copy to user space. 257 * @ptr: Destination address, in user space. 258 * 259 * Context: User context only. This function may sleep if pagefaults are 260 * enabled. 261 * 262 * This macro copies a single simple value from kernel space to user 263 * space. It supports simple types like char and int, but not larger 264 * data types like structures or arrays. 265 * 266 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 267 * to the result of dereferencing @ptr. 268 * 269 * Caller must check the pointer with access_ok() before calling this 270 * function. 271 * 272 * Return: zero on success, or -EFAULT on error. 273 */ 274 #define __put_user(x, ptr) do_put_user_call(put_user_nocheck,x,ptr) 275 276 #define __put_user_size(x, ptr, size, label) \ 277 do { \ 278 __chk_user_ptr(ptr); \ 279 switch (size) { \ 280 case 1: \ 281 __put_user_goto(x, ptr, "b", "iq", label); \ 282 break; \ 283 case 2: \ 284 __put_user_goto(x, ptr, "w", "ir", label); \ 285 break; \ 286 case 4: \ 287 __put_user_goto(x, ptr, "l", "ir", label); \ 288 break; \ 289 case 8: \ 290 __put_user_goto_u64(x, ptr, label); \ 291 break; \ 292 default: \ 293 __put_user_bad(); \ 294 } \ 295 } while (0) 296 297 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 298 299 #ifdef CONFIG_X86_32 300 #define __get_user_asm_u64(x, ptr, label) do { \ 301 unsigned int __gu_low, __gu_high; \ 302 const unsigned int __user *__gu_ptr; \ 303 __gu_ptr = (const void __user *)(ptr); \ 304 __get_user_asm(__gu_low, __gu_ptr, "l", "=r", label); \ 305 __get_user_asm(__gu_high, __gu_ptr+1, "l", "=r", label); \ 306 (x) = ((unsigned long long)__gu_high << 32) | __gu_low; \ 307 } while (0) 308 #else 309 #define __get_user_asm_u64(x, ptr, label) \ 310 __get_user_asm(x, ptr, "q", "=r", label) 311 #endif 312 313 #define __get_user_size(x, ptr, size, label) \ 314 do { \ 315 __chk_user_ptr(ptr); \ 316 switch (size) { \ 317 unsigned char x_u8__; \ 318 case 1: \ 319 __get_user_asm(x_u8__, ptr, "b", "=q", label); \ 320 (x) = x_u8__; \ 321 break; \ 322 case 2: \ 323 __get_user_asm(x, ptr, "w", "=r", label); \ 324 break; \ 325 case 4: \ 326 __get_user_asm(x, ptr, "l", "=r", label); \ 327 break; \ 328 case 8: \ 329 __get_user_asm_u64(x, ptr, label); \ 330 break; \ 331 default: \ 332 (x) = __get_user_bad(); \ 333 } \ 334 } while (0) 335 336 #define __get_user_asm(x, addr, itype, ltype, label) \ 337 asm_volatile_goto("\n" \ 338 "1: mov"itype" %[umem],%[output]\n" \ 339 _ASM_EXTABLE_UA(1b, %l2) \ 340 : [output] ltype(x) \ 341 : [umem] "m" (__m(addr)) \ 342 : : label) 343 344 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT 345 346 #ifdef CONFIG_X86_32 347 #define __get_user_asm_u64(x, ptr, retval) \ 348 ({ \ 349 __typeof__(ptr) __ptr = (ptr); \ 350 asm volatile("\n" \ 351 "1: movl %[lowbits],%%eax\n" \ 352 "2: movl %[highbits],%%edx\n" \ 353 "3:\n" \ 354 ".section .fixup,\"ax\"\n" \ 355 "4: mov %[efault],%[errout]\n" \ 356 " xorl %%eax,%%eax\n" \ 357 " xorl %%edx,%%edx\n" \ 358 " jmp 3b\n" \ 359 ".previous\n" \ 360 _ASM_EXTABLE_UA(1b, 4b) \ 361 _ASM_EXTABLE_UA(2b, 4b) \ 362 : [errout] "=r" (retval), \ 363 [output] "=&A"(x) \ 364 : [lowbits] "m" (__m(__ptr)), \ 365 [highbits] "m" __m(((u32 __user *)(__ptr)) + 1), \ 366 [efault] "i" (-EFAULT), "0" (retval)); \ 367 }) 368 369 #else 370 #define __get_user_asm_u64(x, ptr, retval) \ 371 __get_user_asm(x, ptr, retval, "q", "=r") 372 #endif 373 374 #define __get_user_size(x, ptr, size, retval) \ 375 do { \ 376 unsigned char x_u8__; \ 377 \ 378 retval = 0; \ 379 __chk_user_ptr(ptr); \ 380 switch (size) { \ 381 case 1: \ 382 __get_user_asm(x_u8__, ptr, retval, "b", "=q"); \ 383 (x) = x_u8__; \ 384 break; \ 385 case 2: \ 386 __get_user_asm(x, ptr, retval, "w", "=r"); \ 387 break; \ 388 case 4: \ 389 __get_user_asm(x, ptr, retval, "l", "=r"); \ 390 break; \ 391 case 8: \ 392 __get_user_asm_u64(x, ptr, retval); \ 393 break; \ 394 default: \ 395 (x) = __get_user_bad(); \ 396 } \ 397 } while (0) 398 399 #define __get_user_asm(x, addr, err, itype, ltype) \ 400 asm volatile("\n" \ 401 "1: mov"itype" %[umem],%[output]\n" \ 402 "2:\n" \ 403 ".section .fixup,\"ax\"\n" \ 404 "3: mov %[efault],%[errout]\n" \ 405 " xorl %k[output],%k[output]\n" \ 406 " jmp 2b\n" \ 407 ".previous\n" \ 408 _ASM_EXTABLE_UA(1b, 3b) \ 409 : [errout] "=r" (err), \ 410 [output] ltype(x) \ 411 : [umem] "m" (__m(addr)), \ 412 [efault] "i" (-EFAULT), "0" (err)) 413 414 #endif // CONFIG_CC_ASM_GOTO_OUTPUT 415 416 /* FIXME: this hack is definitely wrong -AK */ 417 struct __large_struct { unsigned long buf[100]; }; 418 #define __m(x) (*(struct __large_struct __user *)(x)) 419 420 /* 421 * Tell gcc we read from memory instead of writing: this is because 422 * we do not write to any memory gcc knows about, so there are no 423 * aliasing issues. 424 */ 425 #define __put_user_goto(x, addr, itype, ltype, label) \ 426 asm_volatile_goto("\n" \ 427 "1: mov"itype" %0,%1\n" \ 428 _ASM_EXTABLE_UA(1b, %l2) \ 429 : : ltype(x), "m" (__m(addr)) \ 430 : : label) 431 432 extern unsigned long 433 copy_from_user_nmi(void *to, const void __user *from, unsigned long n); 434 extern __must_check long 435 strncpy_from_user(char *dst, const char __user *src, long count); 436 437 extern __must_check long strnlen_user(const char __user *str, long n); 438 439 unsigned long __must_check clear_user(void __user *mem, unsigned long len); 440 unsigned long __must_check __clear_user(void __user *mem, unsigned long len); 441 442 #ifdef CONFIG_ARCH_HAS_COPY_MC 443 unsigned long __must_check 444 copy_mc_to_kernel(void *to, const void *from, unsigned len); 445 #define copy_mc_to_kernel copy_mc_to_kernel 446 447 unsigned long __must_check 448 copy_mc_to_user(void *to, const void *from, unsigned len); 449 #endif 450 451 /* 452 * movsl can be slow when source and dest are not both 8-byte aligned 453 */ 454 #ifdef CONFIG_X86_INTEL_USERCOPY 455 extern struct movsl_mask { 456 int mask; 457 } ____cacheline_aligned_in_smp movsl_mask; 458 #endif 459 460 #define ARCH_HAS_NOCACHE_UACCESS 1 461 462 #ifdef CONFIG_X86_32 463 # include <asm/uaccess_32.h> 464 #else 465 # include <asm/uaccess_64.h> 466 #endif 467 468 /* 469 * The "unsafe" user accesses aren't really "unsafe", but the naming 470 * is a big fat warning: you have to not only do the access_ok() 471 * checking before using them, but you have to surround them with the 472 * user_access_begin/end() pair. 473 */ 474 static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len) 475 { 476 if (unlikely(!access_ok(ptr,len))) 477 return 0; 478 __uaccess_begin_nospec(); 479 return 1; 480 } 481 #define user_access_begin(a,b) user_access_begin(a,b) 482 #define user_access_end() __uaccess_end() 483 484 #define user_access_save() smap_save() 485 #define user_access_restore(x) smap_restore(x) 486 487 #define unsafe_put_user(x, ptr, label) \ 488 __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label) 489 490 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 491 #define unsafe_get_user(x, ptr, err_label) \ 492 do { \ 493 __inttype(*(ptr)) __gu_val; \ 494 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), err_label); \ 495 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 496 } while (0) 497 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT 498 #define unsafe_get_user(x, ptr, err_label) \ 499 do { \ 500 int __gu_err; \ 501 __inttype(*(ptr)) __gu_val; \ 502 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err); \ 503 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 504 if (unlikely(__gu_err)) goto err_label; \ 505 } while (0) 506 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT 507 508 /* 509 * We want the unsafe accessors to always be inlined and use 510 * the error labels - thus the macro games. 511 */ 512 #define unsafe_copy_loop(dst, src, len, type, label) \ 513 while (len >= sizeof(type)) { \ 514 unsafe_put_user(*(type *)(src),(type __user *)(dst),label); \ 515 dst += sizeof(type); \ 516 src += sizeof(type); \ 517 len -= sizeof(type); \ 518 } 519 520 #define unsafe_copy_to_user(_dst,_src,_len,label) \ 521 do { \ 522 char __user *__ucu_dst = (_dst); \ 523 const char *__ucu_src = (_src); \ 524 size_t __ucu_len = (_len); \ 525 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \ 526 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \ 527 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \ 528 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \ 529 } while (0) 530 531 #define HAVE_GET_KERNEL_NOFAULT 532 533 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 534 #define __get_kernel_nofault(dst, src, type, err_label) \ 535 __get_user_size(*((type *)(dst)), (__force type __user *)(src), \ 536 sizeof(type), err_label) 537 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT 538 #define __get_kernel_nofault(dst, src, type, err_label) \ 539 do { \ 540 int __kr_err; \ 541 \ 542 __get_user_size(*((type *)(dst)), (__force type __user *)(src), \ 543 sizeof(type), __kr_err); \ 544 if (unlikely(__kr_err)) \ 545 goto err_label; \ 546 } while (0) 547 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT 548 549 #define __put_kernel_nofault(dst, src, type, err_label) \ 550 __put_user_size(*((type *)(src)), (__force type __user *)(dst), \ 551 sizeof(type), err_label) 552 553 #endif /* _ASM_X86_UACCESS_H */ 554 555